Keep a cache of caret painters to avoid recomputing all the time.

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 1909 matching lines @@
             'paint/MediaControlsPainter.cpp',
             'paint/MediaControlsPainter.h',
             'paint/MultiColumnSetPainter.cpp',
             'paint/MultiColumnSetPainter.h',
             'paint/NinePieceImageGrid.cpp',
             'paint/NinePieceImageGrid.h',
             'paint/NinePieceImagePainter.cpp',
             'paint/NinePieceImagePainter.h',
             'paint/ObjectPainter.cpp',
             'paint/ObjectPainter.h',
+            'paint/PaintDataCache.cpp',
+            'paint/PaintDataCache.h',
             'paint/PaintInfo.h',
             'paint/PaintPhase.cpp',
             'paint/PaintPhase.h',
             'paint/PartPainter.cpp',
             'paint/PartPainter.h',
             'paint/ReplacedPainter.cpp',
             'paint/ReplacedPainter.h',
             'paint/ReplicaPainter.cpp',
             'paint/ReplicaPainter.h',
             'paint/RootInlineBoxPainter.cpp',
@@ skipping 2028 matching lines @@
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }