Reviewed by Darin Adler.

        <rdar://problem/5573879> GMail Beta: Crash in when undoing Remove Formating
        
        In the new beta, Google has added some custom code on top of our RemoveFormat
        to work around a bug where fully selected lists aren't removed.  This code corrupts
        the undo stack and causes crashes.  This change fixes two problems with RemoveFormat
        so that Google doesn't have to have any custom code. After checking this in I'll 
        work on bulletproofing the undo stack

        * WebCore.xcodeproj/project.pbxproj: 
        * editing/CompositeEditCommand.cpp:
        (WebCore::CompositeEditCommand::insertLineBreak): Added this convenience method.
        (WebCore::CompositeEditCommand::inputText): Added code to select all inserted text, not
        just the last paragraph.  Added code to support an input string with '\n's.
        * editing/CompositeEditCommand.h:
        * editing/Editor.cpp:
        (WebCore::Editor::removeFormattingAndStyle): Moved code to its own EditCommand.
        * editing/RemoveFormatCommand.cpp: Added. Moved code from removeFormattingAndStyle here.
        (WebCore::RemoveFormatCommand::RemoveFormatCommand):
        (WebCore::RemoveFormatCommand::doApply): Added code to remove fully selected lists.
        * editing/RemoveFormatCommand.h: Added.
        (WebCore::RemoveFormatCommand::editingAction):

LayoutTests:

        Reviewed by Darin Adler.
        
        <rdar://problem/5573879> GMail Beta: Crash in when undoing Remove Formating

        Added to demonstrate fixes:
        * editing/execCommand/5573879.html: Added.
        * platform/mac/editing/execCommand/5573879-expected.checksum: Added.
        * platform/mac/editing/execCommand/5573879-expected.png: Added.
        * platform/mac/editing/execCommand/5573879-expected.txt: Added.
        
        Fixes (RemoveFormat now preserves the selection correctly):
        * platform/mac/editing/execCommand/4920742-1-expected.checksum:
        * platform/mac/editing/execCommand/4920742-1-expected.png:
        * platform/mac/editing/execCommand/4920742-1-expected.txt:
        * platform/mac/editing/execCommand/remove-formatting-2-expected.checksum:
        * platform/mac/editing/execCommand/remove-formatting-2-expected.png:
        * platform/mac/editing/execCommand/remove-formatting-2-expected.txt:
        * platform/mac/editing/execCommand/remove-formatting-expected.checksum:
        * platform/mac/editing/execCommand/remove-formatting-expected.png:
        * platform/mac/editing/execCommand/remove-formatting-expected.txt:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@28126 268f45cc-cd09-0410-ab3c-d52691b4dbfc