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
JiaLiPassion