fix(testabilityPatch): reset cache after memory leak detection

[petebacondarwin]

When you have a test failure in the angular.js project, which also causes a memory leak, such as a failure to dealocate an element or a scope, you often get a false-negative failure for every subsequent test. This change ensures that after such an error, the cache is reset so that subsequent tests can run normally.

[shahata]

I think you can now remove jqLiteCacheSizeInit() and change jqLiteCacheSize() to simply be:

function jqLiteCacheSize() {
  return Object.keys(jqLite.cache).length;
}

[shahata]

The whole purpose of those methods was to handle the fact that cache is not reset between tests :)

[petebacondarwin]

Is that a LGTM for this change then @shahata?

[petebacondarwin]

Although changing that means that we need to clear the cache even if there wasn't a leak.

[shahata]

Yes, LGTM :)