DevTools: [JsDocValidator] Avoid false-positive function receiver-related errors

DevTools: [JsDocValidator] Avoid false-positive function receiver-related errors

The RequiredThisAnnotationChecker has been merged into FunctionReceiverChecker,
so it can now make use of the knowledge whether a nested function
references |this| or not. As such, the receiver checks now rely
on the fact of the |this| usage rather than the presence of the @this annotation.

R=aandrey@chromium.org, aandrey, sergeyv, vsevik

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169643

[aandrey, 2014-03-20 10:55:30]

lgtm

[apavlov, 2014-03-20 11:57:18]

Committed patchset #1 manually as r169643 (presubmit successful).