Defer pushing the parent stack in recalcStyle until StyleResolver::styleForElement()

Source/core/core.gypi

 {
     'variables': {
         'core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSKeyframeRule.idl',
             'css/CSSKeyframesRule.idl',
@@ skipping 827 matching lines @@
             'css/resolver/ScopedStyleTree.h',
             'css/resolver/SharedStyleFinder.cpp',
             'css/resolver/SharedStyleFinder.h',
             'css/resolver/StyleAdjuster.cpp',
             'css/resolver/StyleAdjuster.h',
             'css/resolver/StyleBuilderConverter.cpp',
             'css/resolver/StyleBuilderConverter.h',
             'css/resolver/StyleBuilderCustom.cpp',
             'css/resolver/StyleResolver.cpp',
             'css/resolver/StyleResolver.h',
+            'css/resolver/StyleResolverParentScope.cpp',
+            'css/resolver/StyleResolverParentScope.h',
             'css/resolver/StyleResolverIncludes.h',
             'css/resolver/StyleResolverState.cpp',
             'css/resolver/StyleResolverState.h',
             'css/resolver/StyleResolverStats.cpp',
             'css/resolver/StyleResolverStats.h',
             'css/resolver/StyleResourceLoader.cpp',
             'css/resolver/StyleResourceLoader.h',
             'css/resolver/TransformBuilder.cpp',
             'css/resolver/TransformBuilder.h',
             'css/resolver/ViewportStyleResolver.cpp',
@@ skipping 2693 matching lines @@
             'platform/image-decoders/gif/GIFImageDecoderTest.cpp',
             'platform/image-decoders/jpeg/JPEGImageDecoderTest.cpp',
             'platform/image-decoders/webp/WEBPImageDecoderTest.cpp',
             'platform/testing/FakeWebGraphicsContext3D.h',
             'rendering/RenderOverflowTest.cpp',
             'testing/UnitTestHelpers.h',
             'testing/UnitTestHelpers.cpp',
         ],
     }
 }