Drop [LegacyImplementedInBaseClass] from ParentNode interface

Source/core/core.gypi

 {
     'variables': {
         'deprecated_perl_core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSMediaRule.idl',
@@ skipping 64 matching lines @@
             'dom/MutationObserver.idl',
             'dom/MutationRecord.idl',
             'dom/NamedNodeMap.idl',
             'dom/Node.idl',
             'dom/NodeFilter.idl',
             'dom/NodeIterator.idl',
             'dom/NodeList.idl',
             'dom/Notation.idl',
             'dom/OverflowEvent.idl',
             'dom/PageTransitionEvent.idl',
+            'dom/ParentNode.idl',
             'dom/PopStateEvent.idl',
             'dom/ProcessingInstruction.idl',
             'dom/ProgressEvent.idl',
             'dom/Promise.idl',
             'dom/PromiseResolver.idl',
             'dom/Range.idl',
             'dom/ResourceProgressEvent.idl',
             'dom/SecurityPolicyViolationEvent.idl',
             'dom/Text.idl',
             'dom/TextEvent.idl',
@@ skipping 188 matching lines @@
             'xml/XPathExpression.idl',
             'xml/XPathNSResolver.idl',
             'xml/XPathResult.idl',
             'xml/XSLTProcessor.idl',
         ],
         'python_core_idl_files': [
             'css/RGBColor.idl',
             'css/Rect.idl',
             'dom/ChildNode.idl',
             'dom/DocumentFullscreen.idl',
-            'dom/ParentNode.idl',
             'dom/RequestAnimationFrameCallback.idl',
             'dom/StringCallback.idl',
             'html/VoidCallback.idl',
             'html/canvas/CanvasPattern.idl',
             'html/canvas/EXTFragDepth.idl',
             'html/canvas/OESElementIndexUint.idl',
             'html/canvas/OESTextureFloat.idl',
             'html/canvas/OESTextureFloatLinear.idl',
             'html/canvas/OESTextureHalfFloatLinear.idl',
             'html/canvas/WebGLBuffer.idl',
@@ skipping 1603 matching lines @@
             'dom/NodeRenderStyle.h',
             'dom/NodeTraversal.cpp',
             'dom/NodeTraversal.h',
             'dom/NodeWithIndex.h',
             'dom/Notation.cpp',
             'dom/Notation.h',
             'dom/OverflowEvent.cpp',
             'dom/OverflowEvent.h',
             'dom/PageTransitionEvent.cpp',
             'dom/PageTransitionEvent.h',
+            'dom/ParentNode.h',
             'dom/PendingScript.cpp',
             'dom/PopStateEvent.cpp',
             'dom/PopStateEvent.h',
             'dom/Position.cpp',
             'dom/PositionIterator.cpp',
             'dom/PositionIterator.h',
             'dom/ProcessingInstruction.cpp',
             'dom/ProcessingInstruction.h',
             'dom/ProgressEvent.cpp',
             'dom/ProgressEvent.h',
@@ skipping 1907 matching lines @@
                 'bison_exe': 'bison',
                 # We specify a preprocess so it happens locally and won't get
                 # distributed to goma.
                 # FIXME: /usr/bin/gcc won't exist on OSX forever. We want to
                 # use /usr/bin/clang once we require Xcode 4.x.
                 'preprocessor': '--preprocessor "/usr/bin/gcc -E -P -x c++"'
               }],
          ],
     }
 }