fix(ngMock): annotate $RootScopeDecorator

[shahata]

Closes #10273

[googlebot]

CLAs look good, thanks!

[pkozlowski-opensource]

@shahata would be there a way of testing it somehow?

[shahata]

@pkozlowski-opensource - I'm looking into it, see my comments in the original issue.

[shahata]

@pkozlowski-opensource @caitp - I've added another commit to this PR with a simple mechanism that cleans up $inject from functions that were annotated during each test. This will help detect future problems in angular and also in apps that use strictDi only in part of their tests. WDYT?

[shahata]

So we don't want the $inject cleanup thing?

[pkozlowski-opensource]

@shahata not in 1.3.5. Could you please open a separate PR with it?

[caitp]

@pkozlowski-opensource what he means is "we don't want to use $inject everywhere rather than the array notation?" --- I said I preferred it, because it's a lot easier to read and see what's going on, but honestly I really don't care, it doesn't matter that much.

[shahata]

Actually @pkozlowski-opensource understood me correctly. I'll open a separate PR.