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
protected void setPreferenceStore(IPreferenceStore store) {
		super.setPreferenceStore(store);
		if (getSourceViewerConfiguration() instanceof JavaSourceViewerConfiguration) {
			JavaTextTools textTools= JavaPlugin.getDefault().getJavaTextTools();
			setSourceViewerConfiguration(new JavaSourceViewerConfiguration(textTools.getColorManager(), store, this, IJavaPartitions.JAVA_PARTITIONING));
		}
		if (getSourceViewer() instanceof JavaSourceViewer)
			((JavaSourceViewer)getSourceViewer()).setPreferenceStore(store);
	}
	
	/*
	 * @see IWorkbenchPart#dispose()
	 */
	public void dispose() {
		
		if (fProjectionModelUpdater != null) {
			fProjectionModelUpdater.uninstall();
			fProjectionModelUpdater= null;
		}
		
		if (fProjectionSupport != null) {
			fProjectionSupport.dispose();
			fProjectionSupport= null;
		}
		
		
		fMarkOccurrenceAnnotations= false;
		uninstallOccurrencesFinder();
		
		uninstallOverrideIndicator();