Move PathTraversalState.cpp/.h to platform/

Source/platform/blink_platform.gypi

 {
   'variables': {
     'platform_files': [
       'Clock.cpp',
       'Clock.h',
       'ContentType.cpp',
       'ContentType.h',
       'DateComponents.cpp',
       'DateComponents.h',
       'Decimal.cpp',
@@ skipping 194 matching lines @@
       'geometry/LayoutBoxExtent.cpp',
       'geometry/LayoutBoxExtent.h',
       'geometry/LayoutPoint.h',
       'geometry/LayoutRect.cpp',
       'geometry/LayoutRect.h',
       'geometry/LayoutSize.h',
       'geometry/RoundedRect.cpp',
       'geometry/RoundedRect.h',
       'graphics/angle/ANGLEPlatformBridge.cpp',
       'graphics/angle/ANGLEPlatformBridge.h',
+      'graphics/PathTraversalState.cpp',
+      'graphics/PathTraversalState.h',
       'graphics/TextRun.cpp',
       'graphics/TextRun.h',
       'graphics/TextRunIterator.h',
       'network/DNS.cpp',
       'network/DNS.h',
       'network/HTTPHeaderMap.cpp',
       'network/HTTPHeaderMap.h',
       'network/HTTPParsers.cpp',
       'network/HTTPParsers.h',
       'network/ParsedContentType.cpp',
@@ skipping 78 matching lines @@
       'geometry/RoundedRectTest.cpp',
       'geometry/RoundedRectTest.cpp',
       'testing/ArenaTestHelpers.h',
       'testing/TreeTestHelpers.cpp',
       'testing/TreeTestHelpers.h',
       'text/DateTimeFormatTest.cpp',
       'text/DateTimeFormatTest.cpp',
     ],
   },
 }