https://bugs.webkit.org/show_bug.cgi?id=67832

The compositor thread needs to create a GraphicsContext3D without
actually making it current. In previous attempts at doing this, we
modified all graphics3D creation to not make the contexts current, but
this prove to be shockingly fragile. Since this is a very
Chromium-specific behavior, this patch makes creationForAnotherThread a
method on the private GraphicsContext3D interface.
GraphicsContext3D::create behaves as usual.

Reviewed by Kenneth Russell.

* src/GraphicsContext3DChromium.cpp:
(WebCore::GraphicsContext3DPrivate::createGraphicsContextFromWebContext):
(WebCore::GraphicsContext3DPrivate::createGraphicsContextForAnotherThread):
(WebCore::GraphicsContext3D::create):
* src/GraphicsContext3DPrivate.h:
* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::createLayerTreeHostContext3D):
(WebKit::WebViewImpl::graphicsContext3D):
* tests/MockGraphicsContext3DTest.cpp:
(TEST):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@94971 268f45cc-cd09-0410-ab3c-d52691b4dbfc