feat($http): remove deprecated callback methods: success()/error()

BREAKING CHANGE:

`$http`'s deprecated callback methods `success()` and `error()` have been removed. Use the standard
`then()`/`catch()` promise methods instead.

(Note that the method signatures are different.)

Before:

```js
$http(...).success(function (data, status, headers, config) { ... }));
$http(...).error(function (data, status, headers, config) { ... }));
```

After:

```js
$http(...).then(function (response) {
  var data = response.data;
  var status = response.status;
  var statusText = response.statusText;
  var headers = response.headers;
  var config = response.config;
  ...
}));
$http(...).catch(function (response) {
  var data = response.data;
  var status = response.status;
  var statusText = response.statusText;
  var headers = response.headers;
  var config = response.config;
  ...
}));
```

Author: gkalpak

docs/content/error/$http/legacy.ngdoc

@@ -8,12 +8,6 @@ var JSON_ENDS = {
   '{': /}$/
 };
 var JSON_PROTECTION_PREFIX = /^\)\]\}',?\n/;
-var $httpMinErr = minErr('$http');
-var $httpMinErrLegacyFn = function(method) {
-  return function() {
-    throw $httpMinErr('legacy', 'The method `{0}` on the promise returned from `$http` has been disabled.', method);
-  };
-};
 
 function serializeValue(v) {
   if (isObject(v)) {
@@ -340,30 +334,6 @@ function $HttpProvider() {
     return useApplyAsync;
   };
 
-  var useLegacyPromise = true;
-  /**
-   * @ngdoc method
-   * @name $httpProvider#useLegacyPromiseExtensions
-   * @description
-   *
-   * Configure `$http` service to return promises without the shorthand methods `success` and `error`.
-   * This should be used to make sure that applications work without these methods.
-   *
-   * Defaults to true. If no value is specified, returns the current configured value.
-   *
-   * @param {boolean=} value If true, `$http` will return a promise with the deprecated legacy `success` and `error` methods.
-   *
-   * @returns {boolean|Object} If a value is specified, returns the $httpProvider for chaining.
-   *    otherwise, returns the current configured value.
-   **/
-  this.useLegacyPromiseExtensions = function(value) {
-    if (isDefined(value)) {
-      useLegacyPromise = !!value;
-      return this;
-    }
-    return useLegacyPromise;
-  };
-
   /**
    * @ngdoc property
    * @name $httpProvider#interceptors
@@ -497,14 +467,6 @@ function $HttpProvider() {
      * $httpBackend.flush();
      * ```
      *
-     * ## Deprecation Notice
-     * <div class="alert alert-danger">
-     *   The `$http` legacy promise methods `success` and `error` have been deprecated.
-     *   Use the standard `then` method instead.
-     *   If {@link $httpProvider#useLegacyPromiseExtensions `$httpProvider.useLegacyPromiseExtensions`} is set to
-     *   `false` then these methods will throw {@link $http:legacy `$http/legacy`} error.
-     * </div>
-     *
      * ## Setting HTTP Headers
      *
      * The $http service will automatically add certain HTTP headers to all requests. These defaults
@@ -985,29 +947,6 @@ function $HttpProvider() {
       promise = chainInterceptors(promise, responseInterceptors);
       promise = promise.finally(completeOutstandingRequest);
 
-      if (useLegacyPromise) {
-        promise.success = function(fn) {
-          assertArgFn(fn, 'fn');
-
-          promise.then(function(response) {
-            fn(response.data, response.status, response.headers, config);
-          });
-          return promise;
-        };
-
-        promise.error = function(fn) {
-          assertArgFn(fn, 'fn');
-
-          promise.then(null, function(response) {
-            fn(response.data, response.status, response.headers, config);
-          });
-          return promise;
-        };
-      } else {
-        promise.success = $httpMinErrLegacyFn('success');
-        promise.error = $httpMinErrLegacyFn('error');
-      }
-
       return promise;