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
* 
		 * @param position Position where the action should move the caret
		 */
		protected abstract void setCaretPosition(int position);
	}
	/**
	 * Text navigation action to navigate to the previous sub-word.
	 * 
	 * @since 3.0
	 */
	protected class NavigatePreviousSubWordAction extends PreviousSubWordAction {
		/**
		 * Creates a new navigate previous sub-word action.
		 */
		public NavigatePreviousSubWordAction() {
			super(ST.WORD_PREVIOUS);
		}
		/*
		 * @see org.eclipse.jdt.internal.ui.javaeditor.JavaEditor.PreviousSubWordAction#setCaretPosition(int)
		 */
		protected void setCaretPosition(final int position) {
			getTextWidget().setCaretOffset(modelOffset2WidgetOffset(getSourceViewer(), position));
		}
	}
	/**
	 * Text operation action to delete the previous sub-word.
	 * 
	 * @since 3.0
	 */
	protected class DeletePreviousSubWordAction extends PreviousSubWordAction implements IUpdate {