Fix Function subclassing.

test/mjsunit/es6/classes-subclass-builtins.js

Index: test/mjsunit/es6/classes-subclass-builtins.js
diff --git a/test/mjsunit/es6/classes-subclass-builtins.js b/test/mjsunit/es6/classes-subclass-builtins.js
index 5ecca0ed986f4824573a11f6044007ea4b1e5dc3..db0604249b8c0c69d3e00bd71c6665c08da28c93 100644
--- a/test/mjsunit/es6/classes-subclass-builtins.js
+++ b/test/mjsunit/es6/classes-subclass-builtins.js
@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 // Flags: --allow-natives-syntax --harmony-reflect --harmony-regexp-subclass
-// Flags: --expose-gc
+// Flags: --expose-gc --strong-mode
 
 "use strict";
 
@@ -78,26 +78,52 @@ function checkPrototypeChain(object, constructors) {
     constructor(...args) {
       assertFalse(new.target === undefined);
       super(...args);
+      // Strong functions are not extensible, so don't add fields.
+      if (args[args.length - 1].indexOf("use strong") >= 0) return;
       this.a = 42;
       this.d = 4.2;
       this.o = {foo:153};
     }
   }
-
-  var o = new A("this.foo = 113;");
-  assertTrue(o instanceof Object);
-  assertTrue(o instanceof Function);
-  assertTrue(o instanceof A);
-  assertEquals("function", typeof o);
-  checkPrototypeChain(o, [A, Function, Object]);
-  assertEquals(42, o.a);
-  assertEquals(4.2, o.d);
-  assertEquals(153, o.o.foo);
-  var oo = new o();
+  var sloppy_func = new A("");
+  var strict_func = new A("'use strict';");
+  assertNull(sloppy_func.caller);
+  assertThrows("strict_f.caller");
+  assertNull(Object.getOwnPropertyDescriptor(sloppy_func, "caller").value);
+  assertEquals(undefined, Object.getOwnPropertyDescriptor(strict_func, "caller"));
+
+  var sloppy_func = new A("this.foo = 113;");
+  assertTrue(undefined !== sloppy_func.prototype);
+  sloppy_func.prototype.bar = 377;
+  assertTrue(sloppy_func instanceof Object);
+  assertTrue(sloppy_func instanceof Function);
+  assertTrue(sloppy_func instanceof A);
+  assertEquals("function", typeof sloppy_func);
+  checkPrototypeChain(sloppy_func, [A, Function, Object]);
+  assertEquals(42, sloppy_func.a);
+  assertEquals(4.2, sloppy_func.d);
+  assertEquals(153, sloppy_func.o.foo);
+  var oo = new sloppy_func();
   assertEquals(113, oo.foo);
+  assertEquals(377, oo.bar);
 
-  var o1 = new A("return 312;");
-  assertTrue(%HaveSameMap(o, o1));
+  var sloppy_func1 = new A("return 312;");
+  assertTrue(%HaveSameMap(sloppy_func, sloppy_func1));
+
+
+  var strict_func = new A("'use strict'; this.foo = 113;");
+  assertFalse(%HaveSameMap(strict_func, sloppy_func));
+
+  var strict_func1 = new A("'use strict'; return 312;");
+  assertTrue(%HaveSameMap(strict_func, strict_func1));
+
+
+  var strong_func = new A("'use strong'; this.foo = 113");
+  assertFalse(%HaveSameMap(strong_func, sloppy_func));
+  assertFalse(%HaveSameMap(strong_func, strict_func));
+
+  var strong_func1 = new A("'use strong'; return 312;");
+  assertTrue(%HaveSameMap(strong_func, strong_func1));
 
   gc();
 })();