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/SemanticHighlightingReconciler.java
private List fAddedPositions= new ArrayList();
	
	private List fRemovedPositions= new ArrayList();
	
	private int fNOfRemovedPositions;
	
	
	private Job fJob;
	
	private boolean fCancelJobs;
	
	private Object fJobLock= new Object();
	
	private SemanticHighlightingPresenter fJobPresenter;
	
	private SemanticHighlighting[] fJobSemanticHighlightings;
	
	private Highlighting[] fJobHighlightings;
	
	/*
	 * @see org.eclipse.jdt.internal.ui.text.java.IJavaReconcilingListener#aboutToBeReconciled()
	 */
	public void aboutToBeReconciled() {
		
	}
	
	/*
	 * @see org.eclipse.jdt.internal.ui.text.java.IJavaReconcilingListener#reconciled(CompilationUnit, boolean, IProgressMonitor)
	 */
	public void reconciled(CompilationUnit ast, boolean forced, IProgressMonitor progressMonitor) {