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
fSemanticManager.uninstall();
			fSemanticManager= null;
		}
	}
	
	/**
	 * Returns the Java element wrapped by this editors input.
	 * 
	 * @return the Java element wrapped by this editors input.
	 * @since 3.0
	 */
	abstract protected IJavaElement getInputJavaElement();
	protected void updateStatusLine() {
		ITextSelection selection= (ITextSelection) getSelectionProvider().getSelection();
		Annotation annotation= getAnnotation(selection.getOffset(), selection.getLength());
		setStatusLineErrorMessage(null);
		setStatusLineMessage(null);
		if (annotation != null) {
			try {
				fIsUpdatingAnnotationViews= true;
				updateAnnotationViews(annotation);
			} finally {
				fIsUpdatingAnnotationViews= false;
			}
			if (annotation instanceof IJavaAnnotation && ((IJavaAnnotation) annotation).isProblem())
				setStatusLineMessage(annotation.getText());
		}
	}
	
	/**