Snapshotted plug-ins shadow tree should reset style inheritance
https://bugs.webkit.org/show_bug.cgi?id=116098

Reset the styles such that only injected user-agent stylesheets affect
the rendering of snapshotted plug-ins' shadow content.

Reviewed by Darin Adler.

* html/HTMLPlugInImageElement.cpp:
(WebCore::HTMLPlugInImageElement::didAddUserAgentShadowRoot):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150081 268f45cc-cd09-0410-ab3c-d52691b4dbfc