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
if (currentDistance < 0)
						currentDistance= endOfDocument + currentDistance;
					
					if (currentDistance < distance || currentDistance == distance && p.length < nextAnnotationPosition.length) {
						distance= currentDistance;
						nextAnnotation= a;
						nextAnnotationPosition= p;
					}
				}
			}
		}
		if (containingAnnotationPosition != null && (!currentAnnotation || nextAnnotation == null)) {
			annotationPosition.setOffset(containingAnnotationPosition.getOffset());
			annotationPosition.setLength(containingAnnotationPosition.getLength());
			return containingAnnotation;
		}
		if (nextAnnotationPosition != null) {
			annotationPosition.setOffset(nextAnnotationPosition.getOffset());
			annotationPosition.setLength(nextAnnotationPosition.getLength());
		}
		
		return nextAnnotation;
	}
	
	/**
	 * Returns the annotation overlapping with the given range or <code>null</code>.
	 * 
	 * @param offset the region offset
	 * @param length the region length
	 * @return the found annotation or <code>null</code>