- fixed <rdar://problem/3228554> We should enforce one selection per WebView instead of per window

        Note that this checkin does not mean that we will always maintain a selection in a WebView when
        the focus is elsewhere. Instead it means that there should never be more than one frame containing
        a selection in a WebView, and that it's possible to maintain a selection in a WebView when the focus
        is elsewhere.

        * WebView.subproj/WebView.m:
        (-[WebView searchFor:direction:caseSensitive:wrap:]):
        removed unnecessary and somewhat confusing comment
        (-[WebView selectedFrame]):
        now calls the extracted method -_focusedFrame
        (-[WebView _focusedFrame]):
        new method, extracted from -selectedFrame; returns frame containing first responder, if any
        (-[WebView _findSelectedFrameStartingFromFrame:skippingFrame:]):
        added skippingFrame parameter, which is never returned
        (-[WebView _findSelectedFrameSkippingFrame:]):
        new method, starts from main frame and passes a frame to skip
        (-[WebView _findSelectedFrame]):
        now calls _findSelectedFrameSkippingFrame:nil
        (-[WebView _selectedFrameDidChange]):
        new method, called by WebDocumentText protocol implementors; calls -deselectAll on frame that
        formerly displayed a selection, if any

        * WebView.subproj/WebViewInternal.h:
        added category WebDocumentSelectionExtras, with the one method _selectedFrameDidChange

        * WebView.subproj/WebHTMLView.m:
        (-[WebHTMLView becomeFirstResponder]):
        call -[WebView _selectedFrameDidChange]

        * WebView.subproj/WebPDFView.m:
        (-[WebPDFView becomeFirstResponder]):
        call -[WebView _selectedFrameDidChange]
        (-[WebPDFView resignFirstResponder]):
        deselect all unless webview says not to; note that this doesn't work in all cases due to:
        <rdar://problem/4265966> PDFs continue to show a (secondary) selection when the focus moves elsewhere

        * WebView.subproj/WebTextView.m:
        (-[WebTextView becomeFirstResponder]):
        call -[WebView _selectedFrameDidChange]
        (-[WebTextView resignFirstResponder]):
        deselect all unless webview says not to


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@10578 268f45cc-cd09-0410-ab3c-d52691b4dbfc