Introduce :-internal-shadow-host-has-appearance pseudo class, and apply it to METER element.

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 3183 matching lines @@
             'html/parser/PreloadRequest.cpp',
             'html/parser/ResourcePreloader.cpp',
             'html/parser/TextDocumentParser.cpp',
             'html/parser/TextDocumentParser.h',
             'html/parser/TextResourceDecoder.cpp',
             'html/parser/TextResourceDecoder.h',
             'html/parser/XSSAuditor.cpp',
             'html/parser/XSSAuditor.h',
             'html/parser/XSSAuditorDelegate.cpp',
             'html/parser/XSSAuditorDelegate.h',
-            'html/shadow/AppearanceSwitchElement.cpp',
-            'html/shadow/AppearanceSwitchElement.h',
             'html/shadow/ClearButtonElement.cpp',
             'html/shadow/ClearButtonElement.h',
             'html/shadow/DateTimeEditElement.cpp',
             'html/shadow/DateTimeEditElement.h',
             'html/shadow/DateTimeFieldElement.cpp',
             'html/shadow/DateTimeFieldElement.h',
             'html/shadow/DateTimeFieldElements.cpp',
             'html/shadow/DateTimeFieldElements.h',
             'html/shadow/DateTimeNumericFieldElement.cpp',
             'html/shadow/DateTimeNumericFieldElement.h',
@@ skipping 909 matching lines @@
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'timing/PerformanceBaseTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'workers/WorkerThreadTestHelper.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }