feat(http): allow caching for JSONP requests

Closes #1947
Closes #8356

Author: shahata

src/ng/http.js

@@ -945,7 +945,8 @@ function $HttpProvider() {
       promise.then(removePendingReq, removePendingReq);
 
 
-      if ((config.cache || defaults.cache) && config.cache !== false && config.method == 'GET') {
+      if ((config.cache || defaults.cache) && config.cache !== false &&
+          (config.method === 'GET' || config.method === 'JSONP')) {
         cache = isObject(config.cache) ? config.cache
               : isObject(defaults.cache) ? defaults.cache
               : defaultCache;

test/ng/httpSpec.js

@@ -1217,6 +1217,18 @@ describe('$http', function() {
         expect(callback.mostRecentCall.args[0]).toBe('content');
       }));
 
+      it('should cache JSONP request when cache is provided', inject(function($rootScope) {
+        $httpBackend.expect('JSONP', '/url?cb=JSON_CALLBACK').respond('content');
+        $http({method: 'JSONP', url: '/url?cb=JSON_CALLBACK', cache: cache});
+        $httpBackend.flush();
+
+        $http({method: 'JSONP', url: '/url?cb=JSON_CALLBACK', cache: cache}).success(callback);
+        $rootScope.$digest();
+
+        expect(callback).toHaveBeenCalledOnce();
+        expect(callback.mostRecentCall.args[0]).toBe('content');
+      }));
+
       it('should cache request when cache is provided and no method specified', function () {
         doFirstCacheRequest();