Support the essential part of Shadow DOM v1

third_party/WebKit/Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/EffectModel.idl',
             'animation/AnimationEffectReadOnly.idl',
@@ skipping 2572 matching lines @@
             'dom/shadow/DistributedNodes.h',
             'dom/shadow/ElementShadow.cpp',
             'dom/shadow/ElementShadow.h',
             'dom/shadow/InsertionPoint.cpp',
             'dom/shadow/InsertionPoint.h',
             'dom/shadow/SelectRuleFeatureSet.cpp',
             'dom/shadow/SelectRuleFeatureSet.h',
             'dom/shadow/ShadowRoot.cpp',
             'dom/shadow/ShadowRoot.h',
             'dom/shadow/ShadowRootRareData.h',
+            'dom/shadow/SlotAssignment.cpp',
+            'dom/shadow/SlotAssignment.h',
             'events/AnimationEvent.cpp',
             'events/AnimationEvent.h',
             'events/AnimationPlayerEvent.cpp',
             'events/AnimationPlayerEvent.h',
             'events/ApplicationCacheErrorEvent.cpp',
             'events/ApplicationCacheErrorEvent.h',
             'events/AutocompleteErrorEvent.h',
             'events/BeforeTextInsertedEvent.cpp',
             'events/BeforeTextInsertedEvent.h',
             'events/BeforeUnloadEvent.cpp',
@@ skipping 1349 matching lines @@
             'style/SVGComputedStyleTest.cpp',
             'svg/SVGPathParserTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }