Move paint code from RenderHTMLCanvas to HTMLCanvasPainter.

Source/core/core.gypi

 {
     'includes': [
       'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationEffect.idl',
             'animation/AnimationPlayer.idl',
@@ skipping 1477 matching lines @@
             'paint/BlockFlowPainter.cpp',
             'paint/BlockFlowPainter.h',
             'paint/BoxDecorationData.h',
             'paint/BoxDecorationData.cpp',
             'paint/BoxPainter.cpp',
             'paint/BoxPainter.h',
             'paint/BackgroundImageGeometry.cpp',
             'paint/BackgroundImageGeometry.h',
             'paint/DetailsMarkerPainter.cpp',
             'paint/DetailsMarkerPainter.h',
+            'paint/HTMLCanvasPainter.cpp',
+            'paint/HTMLCanvasPainter.h',
             'paint/InlineFlowBoxPainter.cpp',
             'paint/InlineFlowBoxPainter.h',
             'paint/InlinePainter.cpp',
             'paint/InlinePainter.h',
             'paint/LineBoxListPainter.cpp',
             'paint/LineBoxListPainter.h',
             'paint/ObjectPainter.cpp',
             'paint/ObjectPainter.h',
             'paint/TablePainter.cpp',
             'paint/TablePainter.h',
@@ skipping 2037 matching lines @@
             'rendering/shapes/BoxShapeTest.cpp',
             'rendering/style/OutlineValueTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }