fix($http): propagate status -1 for timed out requests

Fixes #4491
Closes #8756

Author: pkozlowski-opensource

src/ng/http.js

@@ -1289,8 +1289,8 @@ function $HttpProvider() {
        * Resolves the raw $http promise.
        */
       function resolvePromise(response, status, headers, statusText) {
-        // normalize internal statuses to 0
-        status = Math.max(status, 0);
+        //status: HTTP response status code, 0, -1 (aborted by timeout / promise)
+        status = status >= -1 ? status : 0;
 
         (isSuccess(status) ? deferred.resolve : deferred.reject)({
           data: response,

test/ng/httpSpec.js

@@ -1734,7 +1734,7 @@ describe('$http', function() {
         $http({method: 'GET', url: '/some', timeout: canceler.promise}).error(
             function(data, status, headers, config) {
               expect(data).toBeUndefined();
-              expect(status).toBe(0);
+              expect(status).toBe(-1);
               expect(headers()).toEqual({});
               expect(config.url).toBe('/some');
               callback();