Reviewed by levi
        
        <rdar://problem/4549980>
        REGRESSION: "Find Again" can get stuck when searching for string with a trailing space

        * editing/execCommand/findString-expected.checksum: Added.
        * editing/execCommand/findString-expected.png: Added.
        * editing/execCommand/findString-expected.txt: Added.
        * editing/execCommand/findString.html: Added.

WebCore:

        Reviewed by levi
        
        <rdar://problem/4549980>
        REGRESSION: "Find Again" can get stuck when searching for string with a trailing space

        * bridge/mac/FrameMac.h: Moved findString to Frame.
        * bridge/mac/FrameMac.mm: Ditto.
        * bridge/mac/WebCoreFrameBridge.mm:
        (-[WebCoreFrameBridge searchFor:direction:caseSensitive:wrap:]): 
        Convert the NSString to a String.
        * editing/JSEditor.cpp: Added execCommand(FindString, ...)
        * editing/Selection.cpp: Added a constructor for Ranges
        (WebCore::Selection::Selection): 
        * editing/Selection.h:
        * page/Frame.cpp:
        (WebCore::Frame::findString): Moved from FrameMac.  Compare a selection created 
        using the found range with the current selection in case the current selection is
        the found range minus some collapsed whitespace on the edges.
        * page/Frame.h:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@14782 268f45cc-cd09-0410-ab3c-d52691b4dbfc