Reviewed by Darin Adler.

        [Mac] Editor::setComposition() should not trigger correction panel timer.
        https://bugs.webkit.org/show_bug.cgi?id=58049
         <rdar://problem/9226305>

        On Mac OS X that supports autocorrection panel, typing unconfirmed composition (i.e. unconfirmed Japanese or Chinese input)
        should not start autocorrection timer. We added a member variable, m_shouldPreventSpellChecking, to TypingCommand.
        When this value is true, markMisspellingsAfterTyping() will not be called in TypingCommand::typingAddedToOpenCommand().
        m_shouldPreventSpellChecking is set to true in the TypingCommand objects created by Editor::setComposition().

        No new tests. No deterministically reproducible test case. Patch is based on static code analysis. Testing this also requires firing
        autocorrection panel timer, which can not be easily done in automated fashion.

        * editing/Editor.cpp:
        (WebCore::Editor::deleteWithDirection):
        (WebCore::Editor::insertTextWithoutSendingTextEvent):
        (WebCore::Editor::confirmComposition):
        (WebCore::Editor::setComposition):
        * editing/EditorCommand.cpp:
        (WebCore::executeDelete):
        * editing/TypingCommand.cpp:
        (WebCore::TypingCommand::TypingCommand):
        (WebCore::TypingCommand::deleteSelection):
        (WebCore::TypingCommand::deleteKeyPressed):
        (WebCore::TypingCommand::forwardDeleteKeyPressed):
        (WebCore::TypingCommand::insertText):
        (WebCore::TypingCommand::insertLineBreak):
        (WebCore::TypingCommand::insertParagraphSeparator):
        (WebCore::TypingCommand::typingAddedToOpenCommand):
        * editing/TypingCommand.h:
        (WebCore::TypingCommand::create):
        (WebCore::TypingCommand::setShouldPreventSpellChecking):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@83245 268f45cc-cd09-0410-ab3c-d52691b4dbfc