Fixed <rdar://problem/4057004> Data from XMLHTTPRequest is never dealloced

	Fixed <rdar://problem/4057004> Data from XMLHTTPRequest is never dealloced

	WebDataSource keeps an array of all the NSURLResponses associated
	with the load for a page.  This is used to playback delegate messages
	when loading from the page cache.  However, after the document
	has completed it's initial load, we continue to keep track of responses.
	So, this has the consequence of keeping all the responses for a page
	around for the life of the page.  NSURLResponses are now very
	heavy.  They indirectly reference the resource data (via the
	download assessment dictionary).  This fix will keep
	references to responses around for those resources loaded during initial
	page load, but not after that point.

        Reviewed by Ken.

        * WebView.subproj/WebDataSource.m:
        (-[WebDataSource _addResponse:]):
        (-[WebDataSource _stopRecordingResponses]):
        * WebView.subproj/WebDataSourcePrivate.h:
        * WebView.subproj/WebFrame.m:
        (-[WebFrame _opened]):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@8922 268f45cc-cd09-0410-ab3c-d52691b4dbfc