[Qt] Make ImageDiff similar to Chromium's ImageDiff
https://bugs.webkit.org/show_bug.cgi?id=94782

Based on patch by Csaba Osztrogonác.
Reviewed by Jocelyn Turcotte.

The diff image is generated with bright red indicating errors, but letting the base image
shine through so the context of the error-pixel can be identified.

* DumpRenderTree/qt/ImageDiff.cpp:
(main):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146206 268f45cc-cd09-0410-ab3c-d52691b4dbfc
[GTK] Fix WebKit2 builds after r146193
https://bugs.webkit.org/show_bug.cgi?id=112700

Reviewed by Martin Robinson.

Apply changes to the LayerTreeHostGtk class that are analogous to changes made in r146193
to the LayerTreeHostMac class, namely introducing a PageOverlayLayersMap and using that as
the source of GraphicsLayer objects that should be operated on, making it possible to
support multiple page overlays.

* WebProcess/WebPage/gtk/LayerTreeHostGtk.cpp:
(WebKit::LayerTreeHostGtk::initialize):
(WebKit::LayerTreeHostGtk::invalidate):
(WebKit::LayerTreeHostGtk::setNonCompositedContentsNeedDisplay):
(WebKit::LayerTreeHostGtk::setNonCompositedContentsNeedDisplayInRect):
(WebKit::LayerTreeHostGtk::sizeDidChange):
(WebKit::LayerTreeHostGtk::didInstallPageOverlay):
(WebKit::LayerTreeHostGtk::didUninstallPageOverlay):
(WebKit::LayerTreeHostGtk::setPageOverlayNeedsDisplay):
(WebKit::LayerTreeHostGtk::paintContents):
(WebKit::LayerTreeHostGtk::flushPendingLayerChanges):
(WebKit::LayerTreeHostGtk::createPageOverlayLayer):
(WebKit::LayerTreeHostGtk::destroyPageOverlayLayer):
* WebProcess/WebPage/gtk/LayerTreeHostGtk.h:
(LayerTreeHostGtk):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146207 268f45cc-cd09-0410-ab3c-d52691b4dbfc