https://bugs.webkit.org/show_bug.cgi?id=67543
<rdar://problem/10070536>

Reviewed by Darin Adler.

Source/WebCore:

Generalize (begin|end)TransparencyLayer, which now forward
through to (begin|end)PlatformTransparencyLayer, so that
isInTransparencyLayer can exist on every platform.

Make use of isInTransparencyLayer in FontMac to disable
"simple" shadow drawing when the text is being rendered
into a transparency layer.

Test: svg/custom/simple-text-double-shadow.svg

* platform/graphics/GraphicsContext.cpp:
(WebCore::GraphicsContext::GraphicsContext):
(WebCore::GraphicsContext::~GraphicsContext):
(WebCore::GraphicsContext::beginTransparencyLayer):
(WebCore::GraphicsContext::endTransparencyLayer):
(WebCore::GraphicsContext::isInTransparencyLayer):
* platform/graphics/GraphicsContext.h:
* platform/graphics/cairo/GraphicsContextCairo.cpp:
(WebCore::GraphicsContext::beginPlatformTransparencyLayer):
(WebCore::GraphicsContext::endPlatformTransparencyLayer):
(WebCore::GraphicsContext::supportsTransparencyLayers):
* platform/graphics/cairo/GraphicsContextPlatformPrivateCairo.h:
* platform/graphics/cg/GraphicsContextCG.cpp:
(WebCore::GraphicsContext::beginPlatformTransparencyLayer):
(WebCore::GraphicsContext::endPlatformTransparencyLayer):
(WebCore::GraphicsContext::supportsTransparencyLayers):
* platform/graphics/cg/GraphicsContextPlatformPrivateCG.h:
(WebCore::GraphicsContextPlatformPrivate::GraphicsContextPlatformPrivate):
* platform/graphics/haiku/GraphicsContextHaiku.cpp:
(WebCore::GraphicsContext::beginPlatformTransparencyLayer):
(WebCore::GraphicsContext::endPlatformTransparencyLayer):
(WebCore::GraphicsContext::supportsTransparencyLayers):
* platform/graphics/mac/FontMac.mm:
(WebCore::Font::drawGlyphs):
* platform/graphics/openvg/GraphicsContextOpenVG.cpp:
(WebCore::GraphicsContext::beginPlatformTransparencyLayer):
(WebCore::GraphicsContext::endPlatformTransparencyLayer):
(WebCore::GraphicsContext::supportsTransparencyLayers):
* platform/graphics/qt/GraphicsContextQt.cpp:
(WebCore::GraphicsContext::isInTransparencyLayer):
(WebCore::GraphicsContext::beginPlatformTransparencyLayer):
(WebCore::GraphicsContext::endPlatformTransparencyLayer):
(WebCore::GraphicsContext::supportsTransparencyLayers):
* platform/graphics/skia/GraphicsContextSkia.cpp:
(WebCore::GraphicsContext::beginPlatformTransparencyLayer):
(WebCore::GraphicsContext::endPlatformTransparencyLayer):
(WebCore::GraphicsContext::supportsTransparencyLayers):
* platform/graphics/win/FontCGWin.cpp:
(WebCore::drawGDIGlyphs):
* platform/graphics/win/GraphicsContextCGWin.cpp:
(WebCore::GraphicsContext::releaseWindowsContext):
* platform/graphics/win/GraphicsContextCairoWin.cpp:
(WebCore::GraphicsContext::releaseWindowsContext):
* platform/graphics/win/GraphicsContextWin.cpp:
(WebCore::GraphicsContext::getWindowsContext):
* platform/graphics/wince/GraphicsContextWinCE.cpp:
(WebCore::GraphicsContext::beginPlatformTransparencyLayer):
(WebCore::GraphicsContext::endPlatformTransparencyLayer):
(WebCore::GraphicsContext::supportsTransparencyLayers):
* platform/graphics/wx/GraphicsContextWx.cpp:
(WebCore::GraphicsContext::beginPlatformTransparencyLayer):
(WebCore::GraphicsContext::endPlatformTransparencyLayer):
(WebCore::GraphicsContext::supportsTransparencyLayers):
* platform/win/ScrollbarThemeWin.cpp:
* plugins/win/PluginViewWin.cpp:
* rendering/RenderThemeWin.cpp:

LayoutTests:

Add a test ensuring that text with 0px blur CSS shadow doesn't get rendered
with a second shadow when inside a transparency layer.

* platform/mac/svg/custom/simple-text-double-shadow-expected.png: Added.
* platform/mac/svg/custom/simple-text-double-shadow-expected.txt: Added.
* svg/custom/simple-text-double-shadow.svg: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@94897 268f45cc-cd09-0410-ab3c-d52691b4dbfc