Bug 973239 - Promise should call executor and handlers with "undefined" as thisArg. r=benvie

toolkit/modules/Promise-backend.js

@@ -268,7 +268,7 @@ this.Promise = function Promise(aExecutor)
                             .bind(PromiseWalker, this, STATUS_REJECTED);
 
   try {
-    Function.prototype.call.call(aExecutor, this, resolve, reject);
+    aExecutor.call(undefined, resolve, reject);
   } catch (ex) {
     reject(ex);
   }
@@ -704,10 +704,10 @@ Handler.prototype = {
       // the returned value, that can also be another promise.
       if (nextStatus == STATUS_RESOLVED) {
         if (typeof(this.onResolve) == "function") {
-          nextValue = this.onResolve(nextValue);
+          nextValue = this.onResolve.call(undefined, nextValue);
         }
       } else if (typeof(this.onReject) == "function") {
-        nextValue = this.onReject(nextValue);
+        nextValue = this.onReject.call(undefined, nextValue);
         nextStatus = STATUS_RESOLVED;
       }
     } catch (ex) {

toolkit/modules/tests/xpcshell/test_Promise.js

@@ -135,6 +135,24 @@ tests.push(make_promise_test(
     return result;
   }));
 
+// Test that observers get the correct "this" value in strict mode.
+tests.push(
+  make_promise_test(function handlers_this_value(test) {
+    return Promise.resolve().then(
+      function onResolve() {
+        // Since this file is in strict mode, the correct value is "undefined".
+        do_check_eq(this, undefined);
+        throw "reject";
+      }
+    ).then(
+      null,
+      function onReject() {
+        // Since this file is in strict mode, the correct value is "undefined".
+        do_check_eq(this, undefined);
+      }
+    );
+  }));
+
 // Test that observers registered on a pending promise are notified in order.
 tests.push(
   make_promise_test(function then_returns_before_callbacks(test) {
@@ -682,11 +700,10 @@ tests.push(
     }
 
     let executorRan = false;
-    let receiver;
     let promise = new Promise(
       function executor(resolve, reject) {
         executorRan = true;
-        receiver = this;
+        do_check_eq(this, undefined);
         do_check_eq(typeof resolve, "function",
                     "resolve function should be passed to the executor");
         do_check_eq(typeof reject, "function",
@@ -695,7 +712,6 @@ tests.push(
     );
     do_check_instanceof(promise, Promise);
     do_check_true(executorRan, "Executor should execute synchronously");
-    do_check_eq(receiver, promise, "The promise is the |this| in the executor");
 
     // resolve a promise from the executor
     let resolvePromise = new Promise(