Commit graph

87 commits

Author SHA1 Message Date
Alex Rickabaugh
31b396d49c test(core): migrate tests off of Renderer3 interfaces (#46605)
This commit migrates any remaining Angular tests which are using some form
of Renderer3 interfaces. Instead, they're switched to Renderer2.

PR Close #46605
2022-06-30 09:04:56 -07:00
Alex Rickabaugh
5111dbf973 refactor(core): rename the ProceduralRenderer3 interface to Renderer (#46605)
Due to the restrictions of circular dependency checking, we need a separate
internal interface for a renderer. We cannot use `Renderer2` as a type
internally as even importing it as a type incurs a dependency on its
implementation, which creates a major potential for circular dependencies.

Previously this role was served by the `Renderer3` type. As we prepare to
remove the `Renderer3` abstraction (the idea of using `document` as a
differently-shaped renderer), this commit renames `ProceduralRenderer3` to
the more generic term `Renderer`.

`RendererFactory3` is also renamed to the more generic `RendererFactory` for
consistency.

PR Close #46605
2022-06-30 09:04:55 -07:00
Pawel Kozlowski
08733b0566 test(core): remove enableRenderer3 and Renderer3 from tests (#46612)
Remove calls to enableRenderer3 in the functional unit tests.
This effectivelly cuts code paths going through the Renderer3
in the functional tests.

PR Close #46612
2022-06-29 11:18:22 -07:00
Alex Rickabaugh
a322b7d694 refactor(core): disable renderer3 unless explicitly enabled by tests (#46530)
The `Renderer3` abstraction in Angular was an experimental code path in Ivy
which uses direct DOM operations instead of the former `Renderer2` path. To
allow `Renderer2` to tree-shake away, `Renderer3` is the default _unless_
`Renderer2` is provided. It was only an experiment, and never meant to be a
production code path.

However, it's possible for `Renderer3` to leak into user code. This commit
prevents that possibility by causing the `Renderer3` path to throw, unless
an explicit function has been called to enable it.

PR Close #46530
2022-06-28 11:15:54 -07:00
Paul Gschwendtner
95555658cf build: disable bazel nodejs linker to improve stability on windows (#45872)
The NodeJS Bazel linker does not work well on Windows because there
is no sandboxing and linker processes from different tests will attempt
to modify the same `node_modules`, causing concurrency race conditions
and resulting in flakiness.

PR Close #45872
2022-05-04 16:20:57 -07:00
Alex Rickabaugh
1527e8f4c0 refactor(core): change component emit to 'dependencies' (#45672)
Previously, the compiler would represent template dependencies of a
component in its component definition through separate fields (`directives`,
`pipes`).

This commit refactors the compiler/runtime interface to use a single field
(`dependencies`). The runtime component definition object still has separate
`directiveDefs` and `pipeDefs`, which are calculated from the `dependencies`
when the definition is evaluated.

This change is also reflected in partially compiled declarations. To ensure
compatibility with partially compiled code already on NPM, the linker
will still honor the old form of declaration (with separate fields).

PR Close #45672
2022-04-20 05:45:56 -07:00
Kristiyan Kostadinov
69018c9f42 feat(core): allow for injector to be specified when creating an embedded view (#45156)
Adds support for passing in an optional injector when creating an embedded view through `ViewContainerRef.createEmbeddedView` and `TemplateRef.createEmbeddedView`. The injector allows for the DI behavior to be customized within the specific template.

This is a second stab at the changes in #44666. The difference this time is that the new injector acts as a node injector, rather than a module injector.

Fixes #14935.

PR Close #45156
2022-03-02 16:38:00 +00:00
Dylan Hunn
4b936a1014 Revert "feat(core): allow for injector to be specified when creating an embedded view (#45156)" (#45220)
This reverts commit 94c949a60a.

PR Close #45220
2022-03-01 01:04:57 +00:00
Kristiyan Kostadinov
94c949a60a feat(core): allow for injector to be specified when creating an embedded view (#45156)
Adds support for passing in an optional injector when creating an embedded view through `ViewContainerRef.createEmbeddedView` and `TemplateRef.createEmbeddedView`. The injector allows for the DI behavior to be customized within the specific template.

This is a second stab at the changes in #44666. The difference this time is that the new injector acts as a node injector, rather than a module injector.

Fixes #14935.

PR Close #45156
2022-02-28 19:42:26 +00:00
Paul Gschwendtner
c8cd5d5f2c build: switch all instances from ng_rollup_bundle to app_bundle (#44490)
The `ng_rollup_bundle` rule has been replaced with a new rule called
`app_bundle`. This rule replicates the Angular v13 optimization
pipeline in the CLI, so that we can get better benchmarking results.
Also the rule is much simpler to maintain as it relies on ESbuild.

The old `ng_rollup_bundle` rule did rely on e.g. build-optimizer that no
longer has an effect on v13 Angular packages, so technically size
tests/symbol tests were no longer as correct as they were before. This
commit fixes that.

A couple of different changes and their explanation:

* Language-service will no longer use the benchmark rule for creating
  its NPM bundles! It will use plain `rollup_bundle`. ESBuild would have
  been nice but the language-service relies on AMD that ESBuild cannot
  generate (yet?)

* Service-worker ngsw-worker.js file was generated using the benchmark
  bundle rule. This is wrong. We will use a simple ESbuild rule in the
  future. The output is more predictable that way, and we can have a
  clear use of the benchmark bundle rule..

* A couple of benchmarks in `modules/` had to be updated to use e.g.
  `initTableUtils` calls. This is done because with the new rule, all
  files except for the entry-point are considered side-effect free. The
  utilities for benchmarks relied on side-effects in some
  transitively-loaded file (bad practice anyway IMO). We are now
  initializing the utilities using a proper init function that is
  exported...

PR Close #44490
2022-01-04 12:14:14 -08:00
Joey Perrott
00d801122c build: Use Ivy compiler for bazel builds by default (#43862)
Setting the angular_ivy_enabled environment variable to True will default Bazel builds to use the Ivy
compiler rather than defaulting to ViewEngine.

PR Close #43862
2021-10-19 10:06:54 -07:00
Kristiyan Kostadinov
11cd37fae3 fix(core): not invoking object's toString when rendering to the DOM (#39843)
Currently we convert objects to strings using `'' + value` which is quickest,
but it stringifies the value using its `valueOf`, rather than `toString`. These
changes switch to using `String(value)` which has identical performance
and calls the `toString` method as expected. Note that another option
was calling `toString` directly, but benchmarking showed it to be slower.

I've included the benchmark I used to verify the performance so we have it
for future reference and we can reuse it when making changes to `renderStringify`
in the future.

Also for reference, here are the results of the benchmark:

```
Benchmark: renderStringify
 concat: 2.006 ns(0%)
 concat with toString: 2.201 ns(-10%)
 toString: 237.494 ns(-11741%)
 toString with toString: 121.072 ns(-5937%)
 constructor: 2.201 ns(-10%)
 constructor with toString: 2.201 ns(-10%)
 toString mono: 14.536 ns(-625%)
 toString with toString mono: 9.757 ns(-386%)
```

Fixes #38839.

PR Close #39843
2020-11-30 15:49:57 -08:00
Misko Hevery
3b2e5be6cb refactor(core): clean up circular dependencies (#39722)
Clean up circular dependencies in core by pulling symbols out to their
respective files.

PR Close #39722
2020-11-18 09:15:29 -08:00
Misko Hevery
739d745eb5 refactor(core): Cleanup circular dependency between ViewEngine and Ivy ViewContainerRef. (#39621)
`ViewContainerRef` is declared in ViewEngine but it sub-classed in Ivy. This creates a circular
dependency between ViewEngine `ViewContainerRef` which needs to declare `__NG_ELEMENT_ID__` and
ivy factory which needs to create it. The workaround used to be to pass the `ViewContainerRef`
through stack but that created a very convoluted code. This refactoring simply bundles the
two files together and removes the stack workaround making the code simpler to follow.

PR Close #39621
2020-11-16 09:12:46 -08:00
Misko Hevery
453f196c4d refactor(core): Cleanup circular dependency between ViewEngine and Ivy TemplateRef. (#39621)
`TemplateRef` is declared in ViewEngine but it sub-classed in Ivy. This creates a circular
dependency between ViewEngine `TemplateRef` which needs to declare `__NG_ELEMENT_ID__` and
ivy factory which needs to create it. The workaround used to be to pass the `TemplateRef`
through stack but that created a very convoluted code. This refactoring simply bundles the
two files together and removes the stack workaround making the code simpler to follow.

PR Close #39621
2020-11-16 09:12:45 -08:00
Misko Hevery
aa4924513b refactor(core): Cleanup circular dependency between ViewEngine and Ivy ElementRef. (#39621)
`ElementRef` is declared in ViewEngine but it sub-classed in Ivy. This creates a circular
dependency between ViewEngine `ElementRef` which needs to declare `__NG_ELEMENT_ID__` and
ivy factory which needs to create it. The workaround used to be to pass the `ElementRef`
through stack but that created a very convoluted code. This refactoring simply bundles the
two files together and removes the stack workaround making the code simpler to follow.

PR Close #39621
2020-11-16 09:12:45 -08:00
Andrew Kushnir
a83693ddd9 refactor(core): use relative import paths in micro benchmarks (#39142)
This commit updates micro benchmarks to use relative path to Ivy runtime code. Keeping absolute
locations caused issues with build optimizer that retained certain symbols and they appeared in the
output twice.

PR Close #39142
2020-10-14 14:10:13 -07:00
Andrew Kushnir
dd66aa290a test(core): add micro benchmarks for i18n scenarios (#39142)
This commit adds micro benchmarks to run micro benchmarks for i18n-related logic in the
following scenarios:

- i18n static attributes
- i18n attributes with interpolations
- i18n blocks of static text
- i18n blocks of text + interpolations
- simple ICUs
- nested ICUs

First 4 scenarios also have baseline scenarios (non-i18n) so that we can compare i18n perf with
non-i18n logic.

PR Close #39142
2020-10-14 14:10:13 -07:00
Misko Hevery
5db84d7221 refactor(core): Remove TViewNode as it is no longer used. (#38707)
Previous commit change the logic to not rely on the `TViewNode` this
change removes it entirely.

PR Close #38707
2020-09-28 16:15:59 -04:00
Misko Hevery
eb32b6bd6b refactor(core): Remove reliance on TNodeType.View. (#38707)
`TNodeType.View` was created to support inline views. That feature did
not materialize and we have since removed the instructions for it, leave
 an unneeded `TNodeType.View` which was still used in a very
 inconsistent way. This change no longer created `TNodeType.View` (and
 there will be a follow up chang to completely remove it.)

Also simplified the mental model so that `LView[HOST]`/`LView[T_HOST]`
always point to the insertion location of the `LView`.

PR Close #38707
2020-09-28 16:15:59 -04:00
Misko Hevery
9fb541787c refactor(core): Remove host TNode from getOrCreateTNode (#38707)
Host `TNode` was passed into `getOrCreateTNode` just so that we can
compute weather or not we are a root node. This was needed because
`previousOrParentTNode` could have `TNode` from `TView` other then
current `TView`. This is confusing mental model. Previous change
ensured that `previousOrParentTNode` must always be part of `TView`,
which enabled this change to remove the unneeded argument.

PR Close #38707
2020-09-28 16:15:59 -04:00
Paul Gschwendtner
1601ee6f6a refactor(dev-infra): ng_rollup_bundle rule should leverage @bazel/rollup (#37623)
Refactors the `ng_rollup_bundle` rule to a macro that relies on
the `@bazel/rollup` package. This means that the rule no longer
deals with custom ESM5 flavour output, but rather only builds
prodmode ES2015 output. This matches the common build output
in Angular projects, and optimizations done in CLI where
ES2015 is the default optimization input.

The motiviation for this change is:

* Not duplicating rollup Bazel rules. Instead leveraging the official
rollup rule.
* Not dealing with a third TS output flavor in Bazel.The ESM5 flavour has the
potential of slowing down local development (as it requires compilation replaying)
* Updating the rule to be aligned with current CLI optimizations.

This also _fixes_ a bug that surfaced in the old rollup bundle rule.
Code that is unused, is not removed properly. The new rule fixes this by
setting the `toplevel` flag. This instructs terser to remove unused
definitions at top-level. This matches the optimization applied in CLI
projects. Notably the CLI doesn't need this flag, as code is always
wrapped by Webpack. Hence, the unused code eliding runs by default.

PR Close #37623
2020-06-22 10:55:28 -07:00
Joey Perrott
d1ea1f4c7f build: update license headers to reference Google LLC (#37205)
Update the license headers throughout the repository to reference Google LLC
rather than Google Inc, for the required license headers.

PR Close #37205
2020-05-26 14:26:58 -04:00
Andrew Scott
267f844811 docs: update docs for microbenchmarks (#37140)
Update docs in the micro benchmarks to include:
* How to run with no turbo inlining
* Where to find the profiles in the DevTools
* Best way to debug benchmarks (using the profile_in_browser rather than --inspect-brk)

PR Close #37140
2020-05-20 13:37:27 -07:00
Joey Perrott
698b0288be build: reformat repo to new clang@1.4.0 (#36613)
PR Close #36613
2020-04-14 12:08:36 -07:00
Paul Gschwendtner
5615928df9 build: no longer run tslint from within gulp task (#35800)
Switches our tslint setup to the standard `tslint.json` linter excludes.
The set of files that need to be linted is specified through a Yarn script.

For IDEs, open files are linted with the closest tslint configuration, if the
tslint IDE extension is set up, and the source file is not excluded.

We cannot use the language service plugin for tslint as we have multiple nested
tsconfig files, and we don't want to add the plugin to each tsconfig. We
could reduce that bloat by just extending from a top-level tsconfig that
defines the language service plugin, but unfortunately the tslint plugin does
not allow the use of tslint configs which are not part of the tsconfig project.

This is problematic since the tslint configuration is at the project root, and we
don't want to copy tslint configurations next to each tsconfig file.

Additionally, linting of `d.ts` files has been re-enabled. This has been
disabled in the past and a TODO has been left. This commit fixes the
lint issues and re-enables linting.

PR Close #35800
2020-03-03 09:20:49 -08:00
crisbeto
0653db14e7 perf(core): add micro benchmark for destroy hook invocation (#35784)
Adds a micro benchmark which excercises the logic that invokes `ngOnDestroy` hooks.

PR Close #35784
2020-03-03 08:57:58 -08:00
Andrew Kushnir
5bc39f8c8d perf(core): use multiple directives in host bindings micro benchmark (#35736)
This commit updates the host bindings micro benchmark to run tests with mutliple directives (where each directive contains host bindings). The number of directives is configurable as a constant in the micro benchmark file. This change is needed to have an ability to measure/compare perf in different scenarios.

PR Close #35736
2020-02-28 12:26:43 -08:00
Andrew Kushnir
8fed1fe792 perf(core): adding micro benchmark for host bindings (#35705)
This commit adds micro benchmark for host bindings, so that we can assess the impact of changes related to host bindings (for example PR #35568).

PR Close #35705
2020-02-27 13:59:56 -08:00
Miško Hevery
d528dedd50 refactor(ivy): Explicitly pass in TView (#35069)
- Adds `TView` into `LFrame`, read the `TView` from `LView` on `enterView`.
- Before this change the `TView` was ofter looked up from `LView` as `lView[TVIEW]`. This is suboptimal since reading from an Array, requires that the read checks array size before the read. This means that such a read has a much higher cost than reading from the property directly. By passing in the `TView` explicitly it makes the code more explicit and faster.
- Some rearrangements of arguments so that `TView` would come before `LView` for consistency.

PR Close #35069
2020-02-04 12:56:47 -08:00
Miško Hevery
770980de69 test(ivy): fix broken tests (#35069)
PR Close #35069
2020-02-04 12:56:47 -08:00
Misko Hevery
65dbd50594 test(ivy): correct var count in perf benchmarks. (#35071)
These tests are used for perf testing and don't run as part of CI, as a result they bit-rotted. This fixes that. Long term these tests should be run as part of CI.

PR Close #35071
2020-02-03 08:48:41 -08:00
Miško Hevery
9bd9590767 refactor(ivy): change styling to use programmatic API on updates (#34804)
Previously we would write to class/style as strings `element.className` and `element.style.cssText`. Turns out that approach is good for initial render but not good for updates. Updates using this approach are problematic because we have to check to see if there was an out of bound write to style and than perform reconciliation. This also requires the browser to bring up CSS parser which is expensive.

Another problem with old approach is that we had to queue the DOM writes and flush them twice. Once on element advance instruction and once in `hostBindings`. The double flushing is expensive but it also means that a directive can observe that styles are not yet written (they are written after directive executes.)

The new approach uses `element.classList.add/remove` and `element.style.setProperty/removeProperty` API for updates only (it continues to use `element.className` and `element.style.cssText` for initial render as it is cheaper.) The other change is that the styling changes are applied immediately (no queueing). This means that it is the instruction which computes priority. In some circumstances it may result in intermediate writes which are than overwritten with new value. (This should be rare)

Overall this change deletes most of the previous code and replaces it with new simplified implement. The simplification results in code savings.

PR Close #34804
2020-01-24 12:23:19 -08:00
Misko Hevery
76698d38f7 refactor(ivy): Add style reconciliation algorithm (#34004)
This change introduces class/style reconciliation algorithm for DOM elements.
NOTE: The code is not yet hooked up, it will be used by future style algorithm.

Background:
Styling algorithm currently has [two paths](https://hackmd.io/@5zDGNGArSxiHhgvxRGrg-g/rycZk3N5S)
when computing how the style should be rendered.
1. A direct path which concatenates styling and uses `elemnent.className`/`element.style.cssText` and
2. A merge path which uses internal data structures and uses `element.classList.add/remove`/`element.style[property]`.

The situation is confusing and hard to follow/maintain. So a future PR will remove the merge-path and do everything with
direct-path. This however breaks when some other code adds class or style to the element without Angular's knowledge.
If this happens instead of switching from direct-path to merge-path algorithm, this change provides a different mental model
whereby we always do `direct-path` but the code which writes to the DOM detects the situation and reconciles the out of bound write.

The reconciliation process is as follows:
1. Detect that no one has modified `className`/`cssText` and if so just write directly (fast path).
2. If out of bounds write did occur, switch from writing using `className`/`cssText` to `element.classList.add/remove`/`element.style[property]`.
   This does require that the write function computes the difference between the previous Angular expected state and current Angular state.
   (This requires a parser. The advantage of having a parser is that we can support `style="width: {{exp}}px" kind of bindings.`)
   Compute the diff and apply it in non destructive way using `element.classList.add/remove`/`element.style[property]`

Properties of approach:
- If no out of bounds style modification:
  - Very fast code path: Just concatenate string in right order and write them to DOM.
  - Class list order is preserved
- If out of bounds style modification detected:
  - Penalty for parsing
  - Switch to non destructive modification: `element.classList.add/remove`/`element.style[property]`
  - Switch to alphabetical way of setting classes.

PR Close #34004
2020-01-24 12:21:39 -08:00
Andrew Kushnir
8572911e94 test(ivy): class_binding benchmark fixes (#34242)
This commit fixes a couple issues that prevent `class_binding` benchmark from running: moving constants requires by the `benchmark` function before function declaration and referencing correct consts in template instructions.

PR Close #34242
2019-12-11 09:50:23 -08:00
Miško Hevery
8c33f91529 docs: update run instructions (#34090)
PR Close #34090
2019-11-27 10:39:17 -08:00
Joey Perrott
5e3f6d203d build: migrate references and scripts that set to build with ivy via compile=aot to use config=ivy (#33983)
Since config=ivy now sets the define=compile flag and the define=angular_ivy_enabled
flag to cause usage of Ivy, we can update all of the documentation and scripts that
reference compile=aot to use config=ivy.

PR Close #33983
2019-11-26 16:38:40 -05:00
Pawel Kozlowski
31e2bdffa8 perf(ivy): fix creation time micro-benchmarks (#34031)
Micro-benchmarks were broken after we've introduced concept of
DECLARATION_COMPONENT_VIEW on LView (after this change embedded
views must have a pointer to a parent LView).

PR Close #34031
2019-11-25 12:47:58 -05:00
Pawel Kozlowski
5aec1798eb perf(ivy): add micro-benchmark focused on directive input update (#33798)
PR Close #33798
2019-11-19 11:55:59 -08:00
Misko Hevery
b62b11bd6b fix(ivy): Run ChangeDetection on transplanted views (#33644)
https://hackmd.io/@mhevery/rJUJsvv9H

Closes #33393

PR Close #33644
2019-11-12 13:53:54 -08:00
crisbeto
e31f62045d perf(ivy): chain listener instructions (#33720)
Chains multiple listener instructions on a particular element into a single call which results in less generated code. Also handles listeners on templates, host listeners and synthetic host listeners.

PR Close #33720
2019-11-12 09:59:13 -08:00
Matias Niemelä
71b400eb7b test(ivy): introduce a benchmark for duplicate map-based style/class bindings (#33608)
Prior to this patch all the styling benchmarks only tested for
template map-based style/class bindings. Because of each of the bindings
being only present in the template, there was no possibility of
there being any duplicate map-based styling bindings.

This benchmark introduces benchmarking for map-based style/class bindings
that are evaluated from both template bindings as well as directives.

This benchmark can be executed by calling:

```
bazel build //packages/core/test/render3/perf:duplicate_map_based_style_and_class_bindings_lib.min_debug.es2015.js

node dist/bin/packages/core/test/render3/perf/duplicate_map_based_style_and_class_bindings_lib.min_debug.es2015.js
```

The benchmark is also run via the `profile_all.js` script (found in
`packages/core/test/render3/perf/`)

PR Close #33608
2019-11-07 20:34:26 +00:00
Matias Niemelä
8d72a37f3e test(ivy): introduce a benchmark for duplicate style/class bindings (#33600)
Prior to this patch all the styling benchmarks only tested for
template-based style/class bindings. Because of each of the bindings
being only present in the template, there was no possibility of
there being any duplicate bindings. This benchmark introduces
style/class bindings being evaluated from both a template and from
various directives.

This benchmark can be executed by calling:

```
bazel build //packages/core/test/render3/perf:duplicate_style_and_class_bindings_lib.min_debug.es2015.js

node dist/bin/packages/core/test/render3/perf/duplicate_style_and_class_bindings_lib.min_debug.es2015.js
```

The benchmark is also run via the `profile_all.js` script (found in
`packages/core/test/render3/perf/`)

PR Close #33600
2019-11-07 17:50:33 +00:00
Miško Hevery
c25503b142 test(ivy): Have more descriptive names for LView (#33449)
When debugging `LView`s it is easy to get lost since all of them have
the same name. This change does three things:

1. It makes `TView` have an explicit type:
  - `Host`: for the top level `TView` for bootstrap
  - `Component`: for the `TView` which represents components template
  - `Embedded`: for the `TView` which represents an embedded template
2. It changes the name of `LView` to `LHostView`, `LComponentView`, and
  `LEmbeddedView` depending on the `TView` type.
3. For `LComponentView` and `LEmbeddedView` we also append the name of
  of the `context` constructor. The result is that we have `LView`s which
  are name as: `LComponentView_MyComponent` and `LEmbeddedView_NgIfContext`.

The above changes will make it easier to understand the structure of the
application when debugging.

NOTE: All of these are behind `ngDevMode` and will get removed in
production application.

PR Close #33449
2019-11-07 15:33:50 +00:00
Pawel Kozlowski
e89c2dd8d0 perf(ivy): add ngIf-like directive to the ng_template benchmark (#33595)
PR Close #33595
2019-11-06 18:00:48 +00:00
Matias Niemelä
f02213a661 build: restore functionality of the micro benchmarks profile_all.js script (#33494)
The 4b81bb5c97 patch seemingly broke the
`profile_all.js` file due to the file renaming. This patch restores the
functionality of said script.

PR Close #33494
2019-11-01 17:47:49 +00:00
Pawel Kozlowski
df1bef31a4 perf(ivy): add new benchmark focused on template creation (#33511)
PR Close #33511
2019-10-31 22:53:29 +00:00
Miško Hevery
7a280b1a21 test(ivy): clean up class_binding perf tests for readability (#33413)
PR Close #33413
2019-10-25 15:18:07 -07:00
Igor Minar
4b81bb5c97 build: add ng_benchmark macro to run perf benchmarks (#33389)
this makes running and profiling tests much easier. Example usage:

```
yarn bazel run --define=compile=aot //packages/core/test/render3/perf:noop_change_detection
```

See README.md update for more info.

PS: I considered moving the ng_rollup bundle into the macro but I didn't want to make
  too many changes in this PR. If we find running benchmarks in this way useful, we
  should refactor the build file more, and move the ng_rollup_bundle targets into the
  macro.

PR Close #33389
2019-10-25 13:13:32 -07:00
Misko Hevery
6323a35468 test(ivy): support className in micro benchmarks (#33392)
The styling algorithm requires that the `RNode` has a `className`
property in order to execute the fast-path. This changes adds the
emulation of this property.

PR Close #33392
2019-10-25 09:17:52 -07:00