https://bugs.webkit.org/show_bug.cgi?id=88033

Reviewed by Rob Buis.
Patch by Jacky Jiang <zhajiang@rim.com>

PR: 142961
When bridge apps were in carousel mode, the backing store was inactive
as its memory had been released. When we rotated the device, we would
call WebPagPrivate:setViewportSize and resume screen and backing store
to render and blit visible contents. As backing store was inactive and
the window usage was GLES2Usage, we were neither doing backing store
rendering nor direct rendering. Therefore, we drew layers directly
based on the invalid texture contents when blitting contents if
accelerated compositing was enabled.
This patch forces compositing mode to let the accelerated compositing
layer take care of the rendering which can update texture contents
before drawing when backing store is inactive and is openGL compositing.

Reviewed internally by George Staikos and Arvid Nilsson.

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

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@119236 268f45cc-cd09-0410-ab3c-d52691b4dbfc