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/ui/OverrideIndicatorLabelDecorator.java
* @return The resulting decoration.
	 * @throws JavaModelException
	 */
	protected int findInHierarchy(IType type, ITypeHierarchy hierarchy, String name, String[] paramTypes) throws JavaModelException {
		IMethod defining= JavaModelUtil.findMethodDefininition(hierarchy, type, name, paramTypes, false, true);
		if (defining != null) {
			if (JdtFlags.isAbstract(defining)) {
				return JavaElementImageDescriptor.IMPLEMENTS;
			} else {
				return JavaElementImageDescriptor.OVERRIDES;
			}
		}
		return 0;
	}	 
	/* (non-Javadoc)
	 * @see IBaseLabelProvider#addListener(ILabelProviderListener)
	 */
	public void addListener(ILabelProviderListener listener) {
	}
	/* (non-Javadoc)
	 * @see IBaseLabelProvider#dispose()
	 */
	public void dispose() {
		if (fRegistry != null && fUseNewRegistry) {
			fRegistry.dispose();
		}
	}
	/* (non-Javadoc)
	 * @see IBaseLabelProvider#isLabelProperty(Object, String)
	 */