[WK2][CoordinatedGraphics] WKView needs API for handling opacity
https://bugs.webkit.org/show_bug.cgi?id=116032

Patch by Jesus Sanchez-Palencia <jesus.palencia@openbossa.org> on 2013-05-13
Reviewed by Kenneth Rohde Christiansen.

Add WKViewSetOpacity and WKViewOpacity APIs and use them in
WebView.cpp.

* UIProcess/API/C/CoordinatedGraphics/WKView.cpp:
(WKViewSetOpacity):
(WKViewOpacity):
* UIProcess/API/C/CoordinatedGraphics/WKView.h:
* UIProcess/CoordinatedGraphics/WebView.cpp:
(WebKit::WebView::WebView):
(WebKit::WebView::paintToCurrentGLContext):
* UIProcess/CoordinatedGraphics/WebView.h:
(WebKit::WebView::setOpacity):
(WebKit::WebView::opacity):
(WebView):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150012 268f45cc-cd09-0410-ab3c-d52691b4dbfc