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
caret= widgetOffset2ModelOffset(viewer, viewer.getTextWidget().getCaretOffset());
				length= position - caret;
			}
			try {
				viewer.getDocument().replace(caret, length, ""); 
			} catch (BadLocationException exception) {
				
			}
		}
		
		/*
		 * @see org.eclipse.jdt.internal.ui.javaeditor.JavaEditor.NextSubWordAction#findNextPosition(int)
		 */
		protected int findNextPosition(int position) {
			return fIterator.following(position);
		}
		
		/*
		 * @see org.eclipse.ui.texteditor.IUpdate#update()
		 */
		public void update() {
			setEnabled(isEditorInputModifiable());
		}
	}
	/**
	 * Text operation action to select the next sub-word.
	 * 
	 * @since 3.0
	 */
	protected class SelectNextSubWordAction extends NextSubWordAction {