https://bugs.webkit.org/show_bug.cgi?id=101424

Patch by Huang Dongsung <luxtella@company100.net> on 2012-11-08
Reviewed by Noam Rosenthal.

Source/WebCore:

This patch adds ASSERT to TextureMapperLayer while fixing this bug in
WebKit2.

* platform/graphics/texmap/TextureMapperLayer.cpp:
(WebCore::TextureMapperLayer::paintSelf):

Source/WebKit2:

We must remove an invisible TiledBackingStore of CoordinatedGraphicsLayer.
Currently, CoordinatedGraphicsLayer only removes a TiledBackingStore if
!drawsContent() while TextureMapperLayer::updateBackingStore() removes a backing
store if (!m_state.drawsContent || !m_state.contentsVisible || m_size.isEmpty()).
CoordinatedGraphicsLayer must have the same behavior.

In addition, this patch makes LayerTreeRenderer remove a backing store from
GraphicsLayerTextureMapper when CoordinatedBackingStore does not have any tiles.

Test: compositing/nested-direct-image-compositing.html

* UIProcess/CoordinatedGraphics/CoordinatedBackingStore.cpp:
(WebKit::CoordinatedBackingStore::removeTile):
(WebKit::CoordinatedBackingStore::isEmpty):
(WebKit):
(WebKit::CoordinatedBackingStore::commitTileOperations):
* UIProcess/CoordinatedGraphics/CoordinatedBackingStore.h:
(CoordinatedBackingStore):
* UIProcess/CoordinatedGraphics/LayerTreeRenderer.cpp:
(WebKit::LayerTreeRenderer::removeBackingStoreIfNeeded):
(WebKit):
(WebKit::LayerTreeRenderer::removeTile):
* UIProcess/CoordinatedGraphics/LayerTreeRenderer.h:
(LayerTreeRenderer):
* WebProcess/WebPage/CoordinatedGraphics/CoordinatedGraphicsLayer.cpp:
(WebCore::CoordinatedGraphicsLayer::adjustContentsScale):

LayoutTests:

Coordinated Graphics had a bug when a compositing div has a compositing
img with an absolute position property. This test is added to prevent from
a regression.

* compositing/nested-direct-image-compositing-expected.png: Added.
* compositing/nested-direct-image-compositing-expected.txt: Added.
* compositing/nested-direct-image-compositing.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@133955 268f45cc-cd09-0410-ab3c-d52691b4dbfc