Plugin snapshot label should take device resolution and inset into account
https://bugs.webkit.org/show_bug.cgi?id=106619

Reviewed by Simon Fraser.

* rendering/RenderSnapshottedPlugIn.cpp:
(WebCore::RenderSnapshottedPlugIn::paintLabel): Take into account the inset in the label image.
(WebCore::RenderSnapshottedPlugIn::tryToFitStartLabel): Look at the page's device scale, and adjust the label image accordingly.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@139392 268f45cc-cd09-0410-ab3c-d52691b4dbfc