3137110 - REGRESSION: calls from 2nd and subsequent instances of Java 1.4.1 plug-in seem to be ignored

	We had previously made changes to "numb" a plugin controller after its frame
	was tossed or changed content.  We now finish the job by making sure a new
	controller is created when we go to a new page with plugins.  To so this we
	release the old controller whenever we flush the plugins from a page.

        Reviewed by Maciej.

        * WebView.subproj/WebFramePrivate.m:
        (-[WebFrame _detachFromParent]):  Call newly factored code.
        (-[WebFrame _transitionToCommitted:]):  Call newly factored code.
        (-[WebFrame _destroyPluginController]):  New method to tear down plugins.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@3217 268f45cc-cd09-0410-ab3c-d52691b4dbfc