https://bugs.webkit.org/show_bug.cgi?id=120031
<rdar://problem/14606819>

Reviewed by Simon Fraser.

Hit-test for plugin obscurity in the root document. To do this, we also need
to convert the indicator rectangle into root view coordinates before
hit testing its edges.

This resolves the case where an iframe which clips its content was reporting
the indicator as not obscured, despite the fact that it was obscured from the
point of view of the user.

Updated test plugins/unavailable-plugin-indicator-obscurity.html

* rendering/RenderEmbeddedObject.cpp:
(WebCore::RenderEmbeddedObject::isReplacementObscured):

Update the unavailable plugin indicator test to also ensure that plugins are
correctly known to be obscured when contained within and clipped by an <iframe>.

* plugins/unavailable-plugin-indicator-obscurity-expected.txt:
* plugins/unavailable-plugin-indicator-obscurity.html:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@154412 268f45cc-cd09-0410-ab3c-d52691b4dbfc