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 boolean isJavaEditorHoverProperty(String property) {
		return	PreferenceConstants.EDITOR_TEXT_HOVER_MODIFIERS.equals(property);
	}
	
	/**
	 * Return whether the browser like links should be enabled
	 * according to the preference store settings.
	 * @return <code>true</code> if the browser like links should be enabled
	 */
	private boolean isBrowserLikeLinks() {
		IPreferenceStore store= getPreferenceStore();
		return store.getBoolean(BROWSER_LIKE_LINKS);
	}
	
	/**
	 * Enables browser like links.
	 */
	private void enableBrowserLikeLinks() {
		if (fMouseListener == null) {
			fMouseListener= new MouseClickListener();
			fMouseListener.install();
		}
	}
	
	/**
	 * Disables browser like links.
	 */
	private void disableBrowserLikeLinks() {
		if (fMouseListener != null) {
			fMouseListener.uninstall();