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
fActiveRegion= null;
					fRememberedPosition= null;
					deactivate();
				}
			}
		}
		/*
		 * @see org.eclipse.jface.text.ITextInputListener#inputDocumentAboutToBeChanged(org.eclipse.jface.text.IDocument, org.eclipse.jface.text.IDocument)
		 */
		public void inputDocumentAboutToBeChanged(IDocument oldInput, IDocument newInput) {
			if (oldInput == null)
				return;
			deactivate();
			oldInput.removeDocumentListener(this);
		}
		/*
		 * @see org.eclipse.jface.text.ITextInputListener#inputDocumentChanged(org.eclipse.jface.text.IDocument, org.eclipse.jface.text.IDocument)
		 */
		public void inputDocumentChanged(IDocument oldInput, IDocument newInput) {
			if (newInput == null)
				return;
			newInput.addDocumentListener(this);
		}
		/*
		 * @see PaintListener#paintControl(PaintEvent)
		 */
		public void paintControl(PaintEvent event) {	
			if (fActiveRegion == null)
				return;