Harden internal uses of .chain

src/promise.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 152 matching lines @@
       PromiseEnqueue(GET_PRIVATE(this, promiseValue), [onResolve, deferred]);
       break;
     case -1:  // Rejected
       PromiseEnqueue(GET_PRIVATE(this, promiseValue), [onReject, deferred]);
       break;
   }
   return deferred.promise;
 }
 
 function PromiseCatch(onReject) {
-  return this.chain(UNDEFINED, onReject);
+  return this.then(UNDEFINED, onReject);
 }
 
 function PromiseEnqueue(value, tasks) {
   GetMicrotaskQueue().push(function() {
     for (var i = 0; i < tasks.length; i += 2) {
       PromiseHandle(value, tasks[i], tasks[i + 1])
     }
   });
 
   %SetMicrotaskPending(true);
 }
 
 function PromiseHandle(value, handler, deferred) {
   try {
     var result = handler(value);
     if (result === deferred.promise)
       throw MakeTypeError('promise_cyclic', [result]);
     else if (IsPromise(result))
-      result.chain(deferred.resolve, deferred.reject);
+      %_CallFunction(result, deferred.resolve, deferred.reject, PromiseChain);
     else
       deferred.resolve(result);
   } catch(e) {
     // TODO(rossberg): perhaps log uncaught exceptions below.
     try { deferred.reject(e) } catch(e) {}
   }
 }
 
 
 // Multi-unwrapped chaining with thenable coercion.
 
 function PromiseThen(onResolve, onReject) {
   onResolve =
     IS_NULL_OR_UNDEFINED(onResolve) ? PromiseIdResolveHandler : onResolve;
   onReject =
     IS_NULL_OR_UNDEFINED(onReject) ? PromiseIdRejectHandler : onReject;
   var that = this;
   var constructor = this.constructor;
-  return this.chain(
+  return %_CallFunction(
+    this,
     function(x) {
       x = PromiseCoerce(constructor, x);
       return x === that ? onReject(MakeTypeError('promise_cyclic', [x])) :
              IsPromise(x) ? x.then(onResolve, onReject) : onResolve(x);
     },
-    onReject
+    onReject,
+    PromiseChain
   );
 }
 
 PromiseCoerce.table = new $WeakMap;
 
 function PromiseCoerce(constructor, x) {
   if (!IsPromise(x) && IS_SPEC_OBJECT(x)) {
     var then;
     try {
       then = x.then;
@@ skipping 89 matching lines @@
     "resolve", PromiseCast
   ]);
   InstallFunctions($Promise.prototype, DONT_ENUM, [
     "chain", PromiseChain,
     "then", PromiseThen,
     "catch", PromiseCatch
   ]);
 }
 
 SetUpPromise();