fix($httpBackend): use ActiveX XHR when making PATCH requests on IE8

IE8's native XHR doesn't support PATCH requests, but the ActiveX one does.

I'm also removing the noxhr error doc because nobody will ever get that error.

Closes #2518
Closes #5043

4 files changed, 21 insertions, 24 deletions

diff --git a/docs/content/error/httpBackend/noxhr.ngdoc b/docs/content/error/httpBackend/noxhr.ngdoc
deleted file mode 100644
index 3ac5244c..00000000
--- a/docs/content/error/httpBackend/noxhr.ngdoc
+++ /dev/null
@@ -1,9 +0,0 @@
-@ngdoc error
-@name $httpBackend:noxhr
-@fullName Unsupported XHR
-@description
-
-This error occurs in browsers that do not support XmlHttpRequest. AngularJS
-supports Safari, Chrome, Firefox, Opera, IE8 and higher, and mobile browsers
-(Android, Chrome Mobile, iOS Safari). To avoid this error, use an officially
-supported browser.
\ No newline at end of file
diff --git a/src/ng/httpBackend.js b/src/ng/httpBackend.js
index 0bfe2fc3..c72ae4bb 100644
--- a/src/ng/httpBackend.js
+++ b/src/ng/httpBackend.js
@@ -1,12 +1,12 @@
 'use strict';
 
-var XHR = window.XMLHttpRequest || function() {
+function createXhr(method) {
+  // IE8 doesn't support PATCH method, but the ActiveX object does
   /* global ActiveXObject */
-  try { return new ActiveXObject("Msxml2.XMLHTTP.6.0"); } catch (e1) {}
-  try { return new ActiveXObject("Msxml2.XMLHTTP.3.0"); } catch (e2) {}
-  try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch (e3) {}
-  throw minErr('$httpBackend')('noxhr', "This browser does not support XMLHttpRequest.");
-};
+  return (msie <= 8 && lowercase(method) === 'patch')
+      ? new ActiveXObject('Microsoft.XMLHTTP')
+      : new window.XMLHttpRequest();
+}
 
 
 /**
@@ -28,11 +28,11 @@ var XHR = window.XMLHttpRequest || function() {
  */
 function $HttpBackendProvider() {
   this.$get = ['$browser', '$window', '$document', function($browser, $window, $document) {
-    return createHttpBackend($browser, XHR, $browser.defer, $window.angular.callbacks, $document[0]);
+    return createHttpBackend($browser, createXhr, $browser.defer, $window.angular.callbacks, $document[0]);
   }];
 }
 
-function createHttpBackend($browser, XHR, $browserDefer, callbacks, rawDocument) {
+function createHttpBackend($browser, createXhr, $browserDefer, callbacks, rawDocument) {
   var ABORTED = -1;
 
   // TODO(vojta): fix the signature
@@ -57,7 +57,9 @@ function createHttpBackend($browser, XHR, $browserDefer, callbacks, rawDocument)
         delete callbacks[callbackId];
       });
     } else {
-      var xhr = new XHR();
+
+      var xhr = createXhr(method);
+
       xhr.open(method, url, true);
       forEach(headers, function(value, key) {
         if (isDefined(value)) {
diff --git a/src/ngMock/angular-mocks.js b/src/ngMock/angular-mocks.js
index d11ef0c1..fb7ef057 100644
--- a/src/ngMock/angular-mocks.js
+++ b/src/ngMock/angular-mocks.js
@@ -1572,6 +1572,10 @@ function MockHttpExpectation(method, url, data, headers) {
   };
 }
 
+function createMockXhr() {
+  return new MockXhr();
+}
+
 function MockXhr() {
 
   // hack for testing $http, $httpBackend
diff --git a/test/ng/httpBackendSpec.js b/test/ng/httpBackendSpec.js
index 5a392538..7302de00 100644
--- a/test/ng/httpBackendSpec.js
+++ b/test/ng/httpBackendSpec.js
@@ -53,7 +53,7 @@ describe('$httpBackend', function() {
         })
       }
     };
-    $backend = createHttpBackend($browser, MockXhr, fakeTimeout, callbacks, fakeDocument);
+    $backend = createHttpBackend($browser, createMockXhr, fakeTimeout, callbacks, fakeDocument);
     callback = jasmine.createSpy('done');
   }));
 
@@ -250,7 +250,7 @@ describe('$httpBackend', function() {
       expect(response).toBe('response');
     });
 
-    $backend = createHttpBackend($browser, SyncXhr);
+    $backend = createHttpBackend($browser, function() { return new SyncXhr() });
     $backend('GET', '/url', null, callback);
     expect(callback).toHaveBeenCalledOnce();
   });
@@ -426,7 +426,7 @@ describe('$httpBackend', function() {
 
 
     it('should convert 0 to 200 if content', function() {
-      $backend = createHttpBackend($browser, MockXhr);
+      $backend = createHttpBackend($browser, createMockXhr);
 
       $backend('GET', 'file:///whatever/index.html', null, callback);
       respond(0, 'SOME CONTENT');
@@ -437,7 +437,7 @@ describe('$httpBackend', function() {
 
 
     it('should convert 0 to 404 if no content', function() {
-      $backend = createHttpBackend($browser, MockXhr);
+      $backend = createHttpBackend($browser, createMockXhr);
 
       $backend('GET', 'file:///whatever/index.html', null, callback);
       respond(0, '');
@@ -465,7 +465,7 @@ describe('$httpBackend', function() {
 
       try {
 
-        $backend = createHttpBackend($browser, MockXhr);
+        $backend = createHttpBackend($browser, createMockXhr);
 
         $backend('GET', '/whatever/index.html', null, callback);
         respond(0, '');
@@ -480,7 +480,7 @@ describe('$httpBackend', function() {
 
 
     it('should return original backend status code if different from 0', function () {
-      $backend = createHttpBackend($browser, MockXhr);
+      $backend = createHttpBackend($browser, createMockXhr);
 
       // request to http://
       $backend('POST', 'http://rest_api/create_whatever', null, callback);