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
/**
		 * {@inheritDoc}
		 */
		public boolean contains(String name) {
			return fOptions.containsKey(name);
		}
		/**
		 * {@inheritDoc}
		 */
		public void firePropertyChangeEvent(String name, Object oldValue, Object newValue) {
			PropertyChangeEvent event= new PropertyChangeEvent(this, name, oldValue, newValue);
			Object[] listeners= fListeners.getListeners();
			for (int i= 0; i < listeners.length; i++)
				((IPropertyChangeListener) listeners[i]).propertyChange(event);
		}
		/**
		 * {@inheritDoc}
		 */
		public boolean getBoolean(String name) {
			boolean value= BOOLEAN_DEFAULT_DEFAULT;
			String s= (String) fOptions.get(name);
			if (s != null)
				value= s.equals(TRUE);
			return value;
		}
		/**
		 * {@inheritDoc}
		 */
		public boolean getDefaultBoolean(String name) {
			return BOOLEAN_DEFAULT_DEFAULT;