Refactoring: Separate MarkupAccumulator into MarkupFormatter and MarkupAccumulator

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 1332 matching lines @@
             'editing/iterators/FullyClippedStateStack.cpp',
             'editing/iterators/TextIterator.cpp',
             'editing/iterators/TextIterator.h',
             'editing/iterators/TextIteratorTextState.cpp',
             'editing/iterators/TextIteratorTextState.h',
             'editing/iterators/CharacterIterator.cpp',
             'editing/iterators/SimplifiedBackwardsTextIterator.cpp',
             'editing/iterators/WordAwareIterator.cpp',
             'editing/MarkupAccumulator.cpp',
             'editing/MarkupAccumulator.h',
+            'editing/MarkupFormatter.cpp',
+            'editing/MarkupFormatter.h',
             'editing/MergeIdenticalElementsCommand.cpp',
             'editing/MergeIdenticalElementsCommand.h',
             'editing/MoveSelectionCommand.cpp',
             'editing/PlainTextRange.cpp',
             'editing/PlainTextRange.h',
             'editing/PositionWithAffinity.cpp',
             'editing/PositionWithAffinity.h',
             'editing/RemoveCSSPropertyCommand.cpp',
             'editing/RemoveCSSPropertyCommand.h',
             'editing/RemoveFormatCommand.cpp',
@@ skipping 2557 matching lines @@
             'style/ComputedStyleTest.cpp',
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }