prototype: Make sure Element#stopObserving is always chainable.

CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Make sure Element#stopObserving is always chainable.  [sam]
+
 * Event.fire/Element#fire now returns the newly-fired event instead of the event's target element.  [sam]
 
 * Restrict Event.DOMEvents to include only events that can be supported in all browsers.  [sam]

src/event.js

@@ -186,18 +186,20 @@ Object.extend(Event, (function() {
       var id = getEventID(element), name = getDOMEventName(eventName);
       
       if (!handler && eventName) {
-        return getWrappersForEventName(id, eventName).each(function(wrapper) {
+        getWrappersForEventName(id, eventName).each(function(wrapper) {
           element.stopObserving(eventName, wrapper.handler);
-        }) && false;
+        });
+        return element;
         
       } else if (!eventName) {
-        return Object.keys(getCacheForID(id)).each(function(eventName) {
+        Object.keys(getCacheForID(id)).each(function(eventName) {
           element.stopObserving(eventName);
-        }) && false;
+        });
+        return element;
       }
       
       var wrapper = findWrapper(id, eventName, handler);
-      if (!wrapper) return false;
+      if (!wrapper) return element;
       
       if (element.removeEventListener) {
         element.removeEventListener(name, wrapper, false);

test/unit/event.html

@@ -183,6 +183,17 @@
       assertEqual(0, Event.cache[eventID].somethingHappened.length);
     }},
     
+    testStopObservingIsChainable: function() { with(this) {
+      var span = $("span"), observer = function() { };
+      span.observe("somethingHappened", observer);
+      assertEqual(span, span.stopObserving("somethingHappened", observer));
+      span.observe("somethingHappened", observer);
+      assertEqual(span, span.stopObserving("somethingHappened"));
+      span.observe("somethingHappened", observer);
+      assertEqual(span, span.stopObserving());
+      assertEqual(span, span.stopObserving()); // assert it again, after there are no observers
+    }},
+    
     testDocumentContentLoadedEventFiresBeforeWindowLoad: function() { with(this) {
       assert(eventResults.contentLoaded, "contentLoaded");
       assert(eventResults.contentLoaded.endOfDocument, "contentLoaded.endOfDocument");