[generators] Always call function with closure context when resuming.

test/mjsunit/regress/regress-681171-3.js

+// Copyright 2017 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --always-opt --function-context-specialization --verify-heap
+
+function __f_0() {
+}
+try {
+  ( {
+  })();
+} catch(e) {"Caught: " + e; }
+function __f_4() {
+}
+(function __f_5() {
+    var __v_0 = {
+          *['a']() {
+                  yield 2;
+                      }
+            };
+      var __v_3 = __v_0.a();
+       __v_3.next();
+})();
+try {
+  ( {
+  })()();
+} catch(e) {; }