Fix Promise thenable. (#3799)

A single promise can be resolved any number of times due to
thenable functions, but each resolver pair can only be called once.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/jerry/es2015/promise-thenable.js

@@ -0,0 +1,32 @@
+/* Copyright JS Foundation and other contributors, http://js.foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+var counter = 0;
+
+function f() { }
+
+f.then = function(resolve) {
+  if (++counter < 10) {
+    resolve(f)
+  }
+}
+
+new Promise(function(resolve) {
+  resolve(f)
+})
+
+function __checkAsync() {
+  assert(counter == 10)
+}