Relocate box border painting code into BoxBorderPainter

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 1813 matching lines @@
             'page/scrolling/ScrollingCoordinator.cpp',
             'page/scrolling/ScrollingCoordinator.h',
             'page/scrolling/ScrollState.cpp',
             'page/scrolling/ScrollState.h',
             'paint/BackgroundImageGeometry.cpp',
             'paint/BackgroundImageGeometry.h',
             'paint/BlockFlowPainter.cpp',
             'paint/BlockFlowPainter.h',
             'paint/BlockPainter.cpp',
             'paint/BlockPainter.h',
+            'paint/BoxBorderPainter.cpp',
+            'paint/BoxBorderPainter.h',
             'paint/BoxClipper.cpp',
             'paint/BoxClipper.h',
             'paint/BoxDecorationData.cpp',
             'paint/BoxDecorationData.h',
             'paint/BoxPainter.cpp',
             'paint/BoxPainter.h',
             'paint/ClipScope.cpp',
             'paint/ClipScope.h',
             'paint/CompositingRecorder.cpp',
             'paint/CompositingRecorder.h',
@@ skipping 2073 matching lines @@
             'style/ComputedStyleTest.cpp',
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }