Merge 147181 "[chromium] Use widget.parent() for plugin WebMouse..."

Merge 147181 "[chromium] Use widget.parent() for plugin WebMouse..."

> [chromium] Use widget.parent() for plugin WebMouseEvents
> https://bugs.webkit.org/show_bug.cgi?id=113543
> 
> Reviewed by James Robinson.
> 
> In r142571 I switches widget.parent() to widget.root() in the plugin
> WebCore event -> WebMouseEvent creator, to make the converter the
> inverse of the one going the other way and avoid null pointer crashes.
> But the plugin code expects it to be parent() (see
> http://crbug.com/223335).
> 
> * src/WebInputEventConversion.cpp:
> (WebKit::updateWebMouseEventFromWebCoreMouseEvent):
> 

TBR=aelias@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=147288

[aelias_OOO_until_Jul13, 2013-03-31 20:32:55]

Committed patchset #1 manually as r147288.