Bug 75711 AstProvider should not create AST if requested by SelectionListenerWithASTManager
3.1 M2 If SelectionListenerWithASTManager waits for an AST and the editor closes we should not create an AST for that one but return null instead.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
public void updatedTitleImage(Image image) {
		setTitleImage(image);
	}
	
	/*
	 * @see AbstractTextEditor#handlePreferenceStoreChanged(PropertyChangeEvent)
	 */
	protected void handlePreferenceStoreChanged(PropertyChangeEvent event) {
		
		try {			
			ISourceViewer sourceViewer= getSourceViewer();
			if (sourceViewer == null)
				return;
				
			String property= event.getProperty();	
			
			if (isJavaEditorHoverProperty(property))
				updateHoverBehavior();
			
			if (BROWSER_LIKE_LINKS.equals(property)) {
				if (isBrowserLikeLinks())
					enableBrowserLikeLinks();
				else
					disableBrowserLikeLinks();
				return;
			}
			
			if (PreferenceConstants.EDITOR_SYNC_OUTLINE_ON_CURSOR_MOVE.equals(property)) {
				if ((event.getNewValue() instanceof Boolean) && ((Boolean)event.getNewValue()).booleanValue())