Reviewed by Eric Seidel.

        Move MarkupAccumulator from markup.cpp to its own file
        https://bugs.webkit.org/show_bug.cgi?id=47734

        This patch moves the MarkupAccumulator class into its own file.
        There's a lot of clean up left to do, but this patch is a step in the
        right direction.

        No behavior change.

        * Android.mk:
        * CMakeLists.txt:
        * GNUmakefile.am:
        * WebCore.gypi:
        * WebCore.pro:
        * WebCore.vcproj/WebCore.vcproj:
        * WebCore.xcodeproj/project.pbxproj:
        * editing/markup.cpp:
        (WebCore::elementCannotHaveEndTag):
        * editing/markup.h:
        * editing/MarkupAccumulator.h: Added.
        * editing/MarkupAccumulator.cpp: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@69880 268f45cc-cd09-0410-ab3c-d52691b4dbfc