Reviewed by Darin

        - WebCore part of fix for <rdar://problem/4462420> REGRESSION: Mail hangs during 
          Replace All if the replacement string contains the search string
        
        * page/Frame.h:
        * page/Frame.cpp:
        (WebCore::Frame::findString):
        new startInSelection parameter -- if true, search starts looking in selection; if false,
        search starts looking after the selection
        
        * page/mac/WebCoreFrameBridge.h:
        * page/mac/WebCoreFrameBridge.mm:
        (-[WebCoreFrameBridge searchFor:direction:caseSensitive:wrap:startInSelection:]):
        new startInSelection parameter, passed through to Frame::findString()

        * editing/JSEditor.cpp:
        pass false for new findString parameter, to match old behavior

WebKit:

        Reviewed by Darin

        - WebKit part of fix for <rdar://problem/4462420> REGRESSION: Mail hangs during 
          Replace All if the replacement string contains the search string

        * Misc/WebKitVersionChecks.h:
        Added extern "C" so this can be used from .mm files. I don't need this change anymore for
        this fix, but it's still worth fixing now so it doesn't bite anyone later.

        * WebView/WebDocumentPrivate.h:
        Invented new private protocol WebDocumentIncrementalSearching, that has one method. The one
        method is just like the one WebDocumentSearching method, but with an additional parameter.
        We hope to eliminate this dependence on protocols someday, but adding another one as SPI
        seems like it won't make anything worse.
        
        * WebView/WebHTMLView.mm:
        (-[WebHTMLView searchFor:direction:caseSensitive:wrap:]):
        now calls through to new method that has one additional parameter, passing NO to match old behavior
        (-[WebHTMLView searchFor:direction:caseSensitive:wrap:startInSelection:]):
        pass new parameter to bridge
        
        * WebView/WebPDFView.h:
        Declare conformance to WebDocumentIncrementalSearching protocol
        
        * WebView/WebPDFView.mm:
        (-[WebPDFView searchFor:direction:caseSensitive:wrap:]):
        now calls through to new method that has one additional parameter, passing NO to match old behavior
        (-[WebPDFView searchFor:direction:caseSensitive:wrap:startInSelection:]):
        new method, former guts of searchFor:direction:caseSensitive:wrap: but now handles startInSelection
        parameter
        
        * WebView/WebViewPrivate.h:
        Declare new searchFor:direction:caseSensitive:wrap:startInSelection: method, just like existing
        method but with one additional parameter

        * WebView/WebView.mm:
        (-[WebView searchFor:direction:caseSensitive:wrap:]):
        now calls through to new method that has one additional parameter, passing NO to match old behavior
        (-[WebView searchFor:direction:caseSensitive:wrap:startInSelection:]):
        new method, former guts of searchFor:direction:caseSensitive:wrap: but now handles startInSelection
        parameter



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@18928 268f45cc-cd09-0410-ab3c-d52691b4dbfc