Close#42834
In the new version fo Mocha, all global test functions are from `global`
object instead of `Mocha` object. Adn the current `zone.js` Mocha
patch's logic looks like this.
```
global.describe = Mocha.describe = function() {
return originalMochaDescribe.apply(this, arguments);
}
```
and `originalMochaDescribe` is the unpathced Mocha implementation
looks like this
```
function describe() {
return context.describe(...);
}
```
And the `context` will finally delegate to `global.describe()`,
so the current `zone.js` patch causes infinite loop.
This commit will not patch function of `Mocha` object any longer.
PR Close#45047
This partially reverts some changes from 71b9371180 (diff-dd469785fca8680a5b33b1e81c5cfd91R1420)
These broke the g3sync of zone.js because we use the output of the TypeScript compiler directly, rather than rely on the rollup commonjs plugin to define the global symbol
PR Close#31453
