Add a first pass of a class descendant invalidator, and a containing RuleSetAnalyzer

Source/core/core.gypi

 {
     'variables': {
         'core_idl_files': [
             'animation/ElementAnimation.idl',
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSKeyframeRule.idl',
@@ skipping 800 matching lines @@
             'css/StyleSheet.cpp',
             'css/StyleSheet.h',
             'css/StyleSheetContents.cpp',
             'css/StyleSheetContents.h',
             'css/StyleSheetList.cpp',
             'css/StyleSheetList.h',
             'css/VariablesIterator.cpp',
             'css/VariablesIterator.h',
             'css/TreeBoundaryCrossingRules.cpp',
             'css/TreeBoundaryCrossingRules.h',
+            'css/analyzer/DescendantInvalidationSet.h',
+            'css/analyzer/DescendantInvalidationSet.cpp',
+            'css/analyzer/RuleSetAnalyzer.h',
+            'css/analyzer/RuleSetAnalyzer.cpp',
             'css/resolver/AnimatedStyleBuilder.cpp',
             'css/resolver/AnimatedStyleBuilder.h',
             'css/resolver/CSSToStyleMap.cpp',
             'css/resolver/CSSToStyleMap.h',
             'css/resolver/ElementResolveContext.cpp',
             'css/resolver/ElementResolveContext.h',
             'css/resolver/ElementStyleResources.cpp',
             'css/resolver/ElementStyleResources.h',
             'css/resolver/FilterOperationResolver.cpp',
             'css/resolver/FilterOperationResolver.h',
@@ skipping 2420 matching lines @@
             'html/track/vtt/BufferedLineReaderTest.cpp',
             'html/track/vtt/VTTScannerTest.cpp',
             'frame/ImageBitmapTest.cpp',
             'rendering/RenderOverflowTest.cpp',
             'rendering/shapes/BoxShapeTest.cpp',
             'testing/UnitTestHelpers.h',
             'testing/UnitTestHelpers.cpp',
         ],
     }
 }