fix(http): Set response.ok

The ok property was not being set on response objects.
It's now set based on the status code.

Closes #6390
Closes #6503

modules/@angular/http/src/backends/xhr_backend.ts

@@ -69,7 +69,8 @@ export class XHRConnection implements Connection {
           responseOptions = baseResponseOptions.merge(responseOptions);
         }
         let response = new Response(responseOptions);
-        if (isSuccess(status)) {
+        response.ok = isSuccess(status);
+        if (response.ok) {
           responseObserver.next(response);
           // TODO(gdi2290): defer complete if array buffer until done
           responseObserver.complete();

modules/@angular/http/test/backends/xhr_backend_spec.ts

@@ -343,6 +343,34 @@ export function main() {
            existingXHRs[0].dispatchEvent('load');
          }));
 
+      it('should set ok to true on 200 return', inject([AsyncTestCompleter], async => {
+        var statusCode = 200;
+        var connection = new XHRConnection(sampleRequest, new MockBrowserXHR(),
+          new ResponseOptions({status: statusCode}));
+
+        connection.response.subscribe(res => {
+          expect(res.ok).toBe(true);
+          async.done();
+        });
+
+        existingXHRs[0].setStatusCode(statusCode);
+        existingXHRs[0].dispatchEvent('load');
+      }));
+
+      it('should set ok to false on 300 return', inject([AsyncTestCompleter], async => {
+        var statusCode = 300;
+        var connection = new XHRConnection(sampleRequest, new MockBrowserXHR(),
+          new ResponseOptions({status: statusCode}));
+
+        connection.response.subscribe(res => { throw 'should not be called'; }, errRes => {
+          expect(errRes.ok).toBe(false);
+          async.done();
+        });
+
+        existingXHRs[0].setStatusCode(statusCode);
+        existingXHRs[0].dispatchEvent('load');
+      }));
+
       it('should call error and not complete on 300+ codes',
          inject([AsyncTestCompleter], (async: AsyncTestCompleter) => {
            var nextCalled = false;