fix(Http): Fix NoSuchMethodError in Http when cache set to true and

update documentation about cache usage.

Closes dart-archive#1066

Author: mvuksano

lib/core_dom/http.dart

@@ -415,7 +415,8 @@ class Http {
   * - xsrfHeaderName: TBI
   * - xsrfCookieName: TBI
   * - interceptors: Either a [HttpInterceptor] or a [HttpInterceptors]
-  * - cache: Boolean or [Cache].  If true, the default cache will be used.
+  * - cache: Boolean or [Cache].  If true, the default cache will be used. If false, no cache will
+  *      be used. If object of type [Cache] is provided, that object will be used as cache.
   * - timeout: deprecated
 */
   async.Future<HttpResponse> call({
@@ -468,7 +469,7 @@ class Http {
 
       if (cache == false) {
         cache = null;
-      } else if (cache == null) {
+      } else if (cache == true) {
         cache = defaults.cache;
       }
 

test/core_dom/http_spec.dart

@@ -838,6 +838,21 @@ void main() {
             http(method: 'GET', url: '/url', cache: false);
             flush();
           }));
+
+          it('should use default cache if {cache: true} is passed in request config', async(() {
+            http.defaults.cache = cache;
+
+            backend.expect('GET', '/url').respond(200, 'content-cache');
+            http(method: 'GET', url: '/url');
+            flush();
+
+            backend.expect('GET', '/url').respond();
+            http(method: 'GET', url: '/url', cache: true).then(callback);
+            flush();
+
+            expect(callback).toHaveBeenCalledOnce();
+            expect(callback.mostRecentCall.positionalArguments[0].data).toEqual('content-cache');
+          }));
         });
       });