Move cairo/ImageSourceCairo.cpp to ImageSource.cpp in preparation for
merging most of the other ImageSource*.cpp files with it.

Reviewed by Adam Treat.

* GNUmakefile.am:
* WebCore.gypi:
* WebCore.vcproj/WebCore.vcproj:
* platform/graphics/ImageSource.cpp: Copied from WebCore/platform/graphics/cairo/ImageSourceCairo.cpp.
* platform/graphics/cairo/ImageSourceCairo.cpp: Removed.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@47073 268f45cc-cd09-0410-ab3c-d52691b4dbfc