PPT: Closing tab that is hung or chewing 100% CPU leaves abandoned WebProcess.
<http://webkit.org/b/116464>
<rdar://problem/10103795>

Reviewed by Anders Carlsson.

Give the web process a 10 second chance to exit nicely after closing the last tab belonging to it.
This code only runs if there was something on the page (e.g an unload/beforeunload event handler)
preventing the UI process from killing it right away.

* UIProcess/WebProcessProxy.cpp:
(WebKit::WebProcessProxy::WebProcessProxy):
(WebKit::WebProcessProxy::removeWebPage):
(WebKit::WebProcessProxy::forcefulTerminationTimerFired):
* UIProcess/WebProcessProxy.h:
(WebProcessProxy):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150384 268f45cc-cd09-0410-ab3c-d52691b4dbfc