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
private final static String BROWSER_LIKE_LINKS= PreferenceConstants.EDITOR_BROWSER_LIKE_LINKS;
	
	private final static String BROWSER_LIKE_LINKS_KEY_MODIFIER= PreferenceConstants.EDITOR_BROWSER_LIKE_LINKS_KEY_MODIFIER;
	/**
	 * Preference key for key modifier mask of browser like links.
	 * The value is only used if the value of <code>EDITOR_BROWSER_LIKE_LINKS</code>
	 * cannot be resolved to valid SWT modifier bits.
	 * 
	 * @since 2.1.1
	 */
	private final static String BROWSER_LIKE_LINKS_KEY_MODIFIER_MASK= PreferenceConstants.EDITOR_BROWSER_LIKE_LINKS_KEY_MODIFIER_MASK;
	
	protected final static char[] BRACKETS= { '{', '}', '(', ')', '[', ']', '<', '>' };
	
	protected JavaOutlinePage fOutlinePage;
	
	protected String fOutlinerContextMenuId;
	/**
	 * The editor selection changed listener.
	 * 
	 * @since 3.0
	 */
	private EditorSelectionChangedListener fEditorSelectionChangedListener;
	
	protected AbstractSelectionChangedListener fOutlineSelectionChangedListener= new OutlineSelectionChangedListener();
	
	protected JavaPairMatcher fBracketMatcher= new JavaPairMatcher(BRACKETS);
	
	private DefaultEncodingSupport fEncodingSupport;