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 IRegion fHoverRegion;
				private String fHoverInfo;
				private IInformationControlCreator fControlCreator;
				
				InformationProvider(IRegion hoverRegion, String hoverInfo, IInformationControlCreator controlCreator) {
					fHoverRegion= hoverRegion;
					fHoverInfo= hoverInfo;
					fControlCreator= controlCreator;
				}
				/*
				 * @see org.eclipse.jface.text.information.IInformationProvider#getSubject(org.eclipse.jface.text.ITextViewer, int)
				 */
				public IRegion getSubject(ITextViewer textViewer, int invocationOffset) {					
					return fHoverRegion;
				}
				/*
				 * @see org.eclipse.jface.text.information.IInformationProvider#getInformation(org.eclipse.jface.text.ITextViewer, org.eclipse.jface.text.IRegion)
				 */
				public String getInformation(ITextViewer textViewer, IRegion subject) {
					return fHoverInfo;
				}
				/*
				 * @see org.eclipse.jface.text.information.IInformationProviderExtension2#getInformationPresenterControlCreator()
				 * @since 3.0