https://bugs.webkit.org/show_bug.cgi?id=113977
<rdar://problem/13444219>

Source/WebCore:

Reviewed by Tim Horton.

Some articles on USA Today were missing content on load, when a large GraphicsLayer
which did not draw content needed to draw content (and become tiled in the process).

The bug was an ordering dependency in GraphicsLayerCA::commitLayerChangesBeforeSublayers().
swapFromOrToTiledLayer() sets some dirty flags, but for some properties which have
already been committed in the current flush cycle.

Fix by moving the swapFromOrToTiledLayer() to the top of the commit, which is
safe since it only consults GraphicsLayer properties, not CALayer properties.

Test: compositing/tiling/empty-to-tiled.html

* platform/graphics/ca/GraphicsLayerCA.cpp:
(WebCore::GraphicsLayerCA::commitLayerChangesBeforeSublayers):
(WebCore::GraphicsLayerCA::updateGeometry):
(WebCore::GraphicsLayerCA::updateLayerDrawsContent):
(WebCore::GraphicsLayerCA::updateContentsScale):
* platform/graphics/ca/GraphicsLayerCA.h:
(GraphicsLayerCA):

LayoutTests:

Reviewed by Tim Horton.

Ref test that adds visible content to a larger layer.

* compositing/tiling/empty-to-tiled-expected.html: Added.
* compositing/tiling/empty-to-tiled.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147682 268f45cc-cd09-0410-ab3c-d52691b4dbfc