Disentangle blend mode from updateDescendantDependentFlags

Source/core/core.gypi

 {
     'includes': [
       'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationEffect.idl',
             'animation/AnimationPlayer.idl',
@@ skipping 1560 matching lines @@
             'rendering/RenderHTMLCanvas.cpp',
             'rendering/RenderHTMLCanvas.h',
             'rendering/RenderIFrame.cpp',
             'rendering/RenderIFrame.h',
             'rendering/RenderImage.cpp',
             'rendering/RenderImageResource.cpp',
             'rendering/RenderImageResourceStyleImage.cpp',
             'rendering/RenderInline.cpp',
             'rendering/RenderInline.h',
             'rendering/RenderLayer.cpp',
-            'rendering/RenderLayerBlendInfo.cpp',
             'rendering/RenderLayerClipper.cpp',
             'rendering/RenderLayerFilterInfo.cpp',
             'rendering/RenderLayerFilterInfo.h',
             'rendering/RenderLayerModelObject.cpp',
             'rendering/RenderLayerReflectionInfo.cpp',
             'rendering/RenderLayerRepainter.cpp',
             'rendering/RenderLayerScrollableArea.cpp',
             'rendering/RenderLayerStackingNode.cpp',
             'rendering/RenderLayerStackingNodeIterator.cpp',
             'rendering/RenderLineBoxList.cpp',
@@ skipping 1874 matching lines @@
             'rendering/shapes/BoxShapeTest.cpp',
             'rendering/style/OutlineValueTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }