Move Mac related files to Source/platform

Source/core/core.gypi

 {
     'variables': {
         'core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSKeyframeRule.idl',
@@ skipping 2928 matching lines @@
             'platform/image-decoders/png/PNGImageDecoder.cpp',
             'platform/image-decoders/png/PNGImageDecoder.h',
             'platform/image-decoders/webp/WEBPImageDecoder.cpp',
             'platform/image-decoders/webp/WEBPImageDecoder.h',
             'platform/image-encoders/skia/JPEGImageEncoder.cpp',
             'platform/image-encoders/skia/JPEGImageEncoder.h',
             'platform/image-encoders/skia/PNGImageEncoder.cpp',
             'platform/image-encoders/skia/PNGImageEncoder.h',
             'platform/image-encoders/skia/WEBPImageEncoder.cpp',
             'platform/image-encoders/skia/WEBPImageEncoder.h',
-            'platform/mac/BlockExceptions.mm',
             'platform/mac/LocalCurrentGraphicsContext.h',
             'platform/mac/LocalCurrentGraphicsContext.mm',
             'platform/mac/NSScrollerImpDetails.h',
             'platform/mac/NSScrollerImpDetails.mm',
             'platform/mac/ScrollAnimatorMac.h',
             'platform/mac/ScrollAnimatorMac.mm',
             'platform/mac/ScrollElasticityController.h',
             'platform/mac/ScrollElasticityController.mm',
             'platform/mac/ThemeMac.h',
             'platform/mac/ThemeMac.mm',
-            'platform/mac/WebFontCache.mm',
             'platform/mediastream/MediaStreamCenter.cpp',
             'platform/mediastream/MediaStreamCenter.h',
             'platform/mediastream/MediaStreamComponent.cpp',
             'platform/mediastream/MediaStreamComponent.h',
             'platform/mediastream/MediaStreamDescriptor.cpp',
             'platform/mediastream/MediaStreamDescriptor.h',
             'platform/mediastream/RTCDataChannelHandler.cpp',
             'platform/mediastream/RTCDataChannelHandler.h',
             'platform/mediastream/RTCDataChannelHandlerClient.h',
             'platform/mediastream/RTCPeerConnectionHandler.cpp',
@@ skipping 559 matching lines @@
             'platform/graphics/gpu/DrawingBufferTest.cpp',
             'platform/image-decoders/ImageDecoderTest.cpp',
             'platform/image-decoders/gif/GIFImageDecoderTest.cpp',
             'platform/image-decoders/jpeg/JPEGImageDecoderTest.cpp',
             'platform/image-decoders/webp/WEBPImageDecoderTest.cpp',
             'platform/testing/FakeWebGraphicsContext3D.h',
             'rendering/RenderOverflowTest.cpp',
         ],
     }
 }