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
public boolean isLabelProperty(Object element, String property) {
		return true;
	}
	/* (non-Javadoc)
	 * @see IBaseLabelProvider#removeListener(ILabelProviderListener)
	 */
	public void removeListener(ILabelProviderListener listener) {
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.jface.viewers.ILightweightLabelDecorator#decorate(java.lang.Object, org.eclipse.jface.viewers.IDecoration)
	 */
	public void decorate(Object element, IDecoration decoration) { 
		int adornmentFlags= computeAdornmentFlags(element);
		if ((adornmentFlags & JavaElementImageDescriptor.IMPLEMENTS) != 0) {
			if ((adornmentFlags & JavaElementImageDescriptor.SYNCHRONIZED) != 0) {
				decoration.addOverlay(JavaPluginImages.DESC_OVR_SYNCH_AND_IMPLEMENTS);
			} else {
				decoration.addOverlay(JavaPluginImages.DESC_OVR_IMPLEMENTS);
			}
		} else if ((adornmentFlags & JavaElementImageDescriptor.OVERRIDES) != 0) {
			if ((adornmentFlags & JavaElementImageDescriptor.SYNCHRONIZED) != 0) {
				decoration.addOverlay(JavaPluginImages.DESC_OVR_SYNCH_AND_OVERRIDES);
			} else {
				decoration.addOverlay(JavaPluginImages.DESC_OVR_OVERRIDES);
			}
		}
	}
}