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
if (required == IShowInTargetList.class) {
			return new IShowInTargetList() {
				public String[] getShowInTargetIds() {
					return new String[] { JavaUI.ID_PACKAGES, IPageLayout.ID_OUTLINE, IPageLayout.ID_RES_NAV };
				}
			};
		}
		
		if (fProjectionSupport != null) {
			Object adapter= fProjectionSupport.getAdapter(getSourceViewer(), required);
			if (adapter != null)
				return adapter;
		}
			
		return super.getAdapter(required);
	}
	
	/**
	 * React to changed selection.
	 * 
	 * @since 3.0
	 */
	protected void selectionChanged() {
		if (getSelectionProvider() == null)
			return;
		ISourceReference element= computeHighlightRangeSourceReference();
		if (getPreferenceStore().getBoolean(PreferenceConstants.EDITOR_SYNC_OUTLINE_ON_CURSOR_MOVE))
			synchronizeOutlinePage(element);
		setSelection(element, false);
		updateStatusLine();