[BlackBerry] Hook up frame render begin/end in PerformanceMonitor
https://bugs.webkit.org/show_bug.cgi?id=116110

Patch by Andrew Lo <anlo@rim.com> on 2013-05-14
Reviewed by Rob Buis.

Internally reviewed by Jeff Rogers, Jonathan Jiang.
Internal PR 299155.

Mark frame render begin & end for BlackBerry performance monitoring
in blitVisibleContents.

* Api/BackingStore.cpp:
(BlackBerry::WebKit::BackingStorePrivate::blitVisibleContents):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150082 268f45cc-cd09-0410-ab3c-d52691b4dbfc