fix($httpBackend): cancelled JSONP requests should not throw error

src/ng/httpBackend.js

@@ -54,7 +54,7 @@ function createHttpBackend($browser, createXhr, $browserDefer, callbacks, rawDoc
         } else {
           completeRequest(callback, status || -2);
         }
-        delete callbacks[callbackId];
+        callbacks[callbackId] = angular.noop;
       });
     } else {
 

test/ng/httpBackendSpec.js

@@ -328,7 +328,7 @@ describe('$httpBackend', function() {
         script.onload();
       }
 
-      expect(callbacks[callbackId]).toBeUndefined();
+      expect(callbacks[callbackId]).toBe(angular.noop);
       expect(fakeDocument.body.removeChild).toHaveBeenCalledOnceWith(script);
     });
 
@@ -395,7 +395,7 @@ describe('$httpBackend', function() {
     });
 
 
-    it('should abort request on timeout', function() {
+    it('should abort request on timeout and replace callback with noop', function() {
       callback.andCallFake(function(status, response) {
         expect(status).toBe(-1);
       });
@@ -404,9 +404,14 @@ describe('$httpBackend', function() {
       expect(fakeDocument.$$scripts.length).toBe(1);
       expect(fakeTimeout.delays[0]).toBe(2000);
 
+      var script = fakeDocument.$$scripts.shift(),
+        callbackId = script.src.match(SCRIPT_URL)[2];
+
       fakeTimeout.flush();
       expect(fakeDocument.$$scripts.length).toBe(0);
       expect(callback).toHaveBeenCalledOnce();
+
+      expect(callbacks[callbackId]).toBe(angular.noop);
     });