Reviewed by Gustavo Noronha Silva.

        Move Cairo-related font code from platform/graphics/gtk to
        platform/graphics/cairo, so other ports may use them.
        http://webkit.org/b/35539

        * GNUmakefile.am:
        * platform/graphics/cairo/FontCacheCairo.cpp: Copied from WebCore/platform/graphics/gtk/FontCacheGtk.cpp.
        * platform/graphics/cairo/FontCustomPlatformData.cpp: Copied from WebCore/platform/graphics/gtk/FontCustomPlatformData.cpp.
        * platform/graphics/cairo/FontCustomPlatformData.h: Copied from WebCore/platform/graphics/gtk/FontCustomPlatformData.h.
        * platform/graphics/cairo/FontPlatformData.h: Copied from WebCore/platform/graphics/gtk/FontPlatformData.h.
        * platform/graphics/cairo/FontPlatformDataCairo.cpp: Copied from WebCore/platform/graphics/gtk/FontPlatformDataGtk.cpp.
        * platform/graphics/cairo/GlyphPageTreeNodeCairo.cpp: Copied from WebCore/platform/graphics/gtk/GlyphPageTreeNodeGtk.cpp.
        * platform/graphics/cairo/SimpleFontDataCairo.cpp: Copied from WebCore/platform/graphics/gtk/SimpleFontDataGtk.cpp.
        * platform/graphics/gtk/FontCacheGtk.cpp: Removed.
        * platform/graphics/gtk/FontCustomPlatformData.cpp: Removed.
        * platform/graphics/gtk/FontCustomPlatformData.h: Removed.
        * platform/graphics/gtk/FontPlatformData.h: Removed.
        * platform/graphics/gtk/FontPlatformDataGtk.cpp: Removed.
        * platform/graphics/gtk/GlyphPageTreeNodeGtk.cpp: Removed.
        * platform/graphics/gtk/SimpleFontDataGtk.cpp: Removed.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@55510 268f45cc-cd09-0410-ab3c-d52691b4dbfc