Don't dispatch delayed click if snapshotted plugin was triggered by a click on the label
https://bugs.webkit.org/show_bug.cgi?id=113982

Reviewed by Tim Horton.

We regressed the way clicks were sent on to restarted plugins when we moved to a
Shadow Root - we were always sending the click. We should only send the click
on if the user clicked on the main plugin content, and not send it when you
click directly on the label.

* html/HTMLPlugInImageElement.cpp:
(WebCore::HTMLPlugInImageElement::didAddUserAgentShadowRoot): Keep a reference to the container and label.
(WebCore::HTMLPlugInImageElement::partOfSnapshotLabel): New method that detects if a Node was part
    of the snapshot label.
(WebCore::HTMLPlugInImageElement::userDidClickSnapshot): Only record the event if you should forward it on.
* html/HTMLPlugInImageElement.h:
(HTMLPlugInImageElement): New parameter to userDidClickSnapshot and member variables for shadow content.
* rendering/RenderSnapshottedPlugIn.cpp:
(WebCore::RenderSnapshottedPlugIn::handleEvent): Ask the plugin if the clicked target was the snapshot label.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147693 268f45cc-cd09-0410-ab3c-d52691b4dbfc