Add outline files for StylePropertyMap.

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 28 matching lines @@
             'css/StyleSheet.idl',
             'css/StyleSheetList.idl',
             'css/WebKitCSSMatrix.idl',
             'css/cssom/CalcLength.idl',
             'css/cssom/KeywordValue.idl',
             'css/cssom/LengthValue.idl',
             'css/cssom/MatrixTransformComponent.idl',
             'css/cssom/NumberValue.idl',
             'css/cssom/ScaleTransformComponent.idl',
             'css/cssom/SimpleLength.idl',
+            'css/cssom/StylePropertyMap.idl',
             'css/cssom/StyleValue.idl',
             'css/cssom/TransformComponent.idl',
             'css/cssom/TransformValue.idl',
             'dom/ArrayBuffer.idl',
             'dom/ArrayBufferView.idl',
             'dom/Attr.idl',
             'dom/CDATASection.idl',
             'dom/CharacterData.idl',
             'dom/ClientRect.idl',
             'dom/ClientRectList.idl',
@@ skipping 1193 matching lines @@
             'css/StyleRuleImport.h',
             'css/StyleRuleKeyframe.cpp',
             'css/StyleRuleKeyframe.h',
             'css/StyleRuleNamespace.h',
             'css/StyleSheet.cpp',
             'css/StyleSheet.h',
             'css/StyleSheetContents.cpp',
             'css/StyleSheetContents.h',
             'css/StyleSheetList.cpp',
             'css/StyleSheetList.h',
+            'css/cssom/ImmutableStylePropertyMap.h',
             'css/cssom/StyleCalcLength.cpp',
             'css/cssom/StyleCalcLength.h',
             'css/cssom/KeywordValue.cpp',
             'css/cssom/KeywordValue.h',
             'css/cssom/LengthValue.cpp',
             'css/cssom/LengthValue.h',
             'css/cssom/MatrixTransformComponent.cpp',
             'css/cssom/MatrixTransformComponent.h',
+            'css/cssom/MutableStylePropertyMap.h',
             'css/cssom/NumberValue.h',
             'css/cssom/ScaleTransformComponent.cpp',
             'css/cssom/ScaleTransformComponent.h',
             'css/cssom/SimpleLength.cpp',
             'css/cssom/SimpleLength.h',
+            'css/cssom/StylePropertyMap.cpp',
+            'css/cssom/StylePropertyMap.h',
             'css/cssom/StyleValue.cpp',
             'css/cssom/StyleValue.h',
             'css/cssom/TransformComponent.h',
             'css/cssom/TransformValue.cpp',
             'css/cssom/TransformValue.h',
             'css/invalidation/InvalidationSet.cpp',
             'css/invalidation/InvalidationSet.h',
             'css/invalidation/PendingInvalidations.h',
             'css/invalidation/StyleInvalidator.cpp',
             'css/invalidation/StyleInvalidator.h',
@@ skipping 2744 matching lines @@
             'style/SVGComputedStyleTest.cpp',
             'svg/SVGPathParserTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }