the createCustomEvent function's pupose is to create customEvents
even on browsers where `CustomEvent` is not a constructor,
`CustomEvent` is currently available in all supported browsers (since
IE11 support has ended), so remove the function as it is no longer
needed
PR Close#44703
Although in SSR we patch the global prototypes with DOM globals
like Element and Node, this patch does not occur before the
matches function is called in Angular Elements. This is similar
to the behavior in @angular/upgrade.
Fixes#24551
PR Close#37799
Detect server environment by checking `typeof window` and schedule render immediately instead of waiting for RAF.
This does not make Angular Elements work on platform-server. This is just the first step.
PR Close#23324
This PR was merged without API docs and general rollout plan.
We can't release this as is in 5.1 without a plan for documentation, cli integration, etc.
