[WinCairo] Accelerated compositing should be disabled when graphics card does not...

[WinCairo] Accelerated compositing should be disabled when graphics card does not support it.
https://bugs.webkit.org/show_bug.cgi?id=140667

Patch by peavo@outlook.com <peavo@outlook.com> on 2015-02-11
Reviewed by Alex Christensen.

* WebCoreSupport/AcceleratedCompositingContext.cpp:
(AcceleratedCompositingContext::scrollNonCompositedContents):
(AcceleratedCompositingContext::acceleratedCompositingAvailable):
* WebCoreSupport/AcceleratedCompositingContext.h:
* WebView.cpp:
(WebView::notifyPreferencesChanged):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@179962 268f45cc-cd09-0410-ab3c-d52691b4dbfc