Fix <rdar://problem/5329481> Character range rect code for IME support needs to be crossplatform

        Move -[WebCoreFrameBridge firstRectForDOMRange:] to Frame::firstRectForRange

        * page/Frame.cpp:
        (WebCore::Frame::firstRectForRange):
        * page/Frame.h:
        * page/mac/WebCoreFrameBridge.mm:
        (-[WebCoreFrameBridge firstRectForDOMRange:]):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@24222 268f45cc-cd09-0410-ab3c-d52691b4dbfc