[runtime] Throw exception for derived constructors in correct context.

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index cb092f2f2d72890080ad926628da7af870478ea9..33a11e3902494ba69decf931524367fbd6534d04 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -117,7 +117,8 @@ void Builtins::Generate_InOptimizationQueue(MacroAssembler* masm) {
 
 static void Generate_JSConstructStubHelper(MacroAssembler* masm,
                                            bool is_api_function,
-                                           bool create_implicit_receiver) {
+                                           bool create_implicit_receiver,
+                                           bool check_derived_construct) {
   // ----------- S t a t e -------------
   //  -- rax: number of arguments
   //  -- rdi: constructor function
@@ -357,6 +358,19 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     // Leave construct frame.
   }
 
+  // ES6 9.2.2. Step 13+
+  // Check that the result is not a Smi, indicating that the constructor result
+  // from a derived class is neither undefined nor an Object.
+  if (check_derived_construct) {
+    Label dont_throw;
+    __ JumpIfNotSmi(rax, &dont_throw);
+    {
+      FrameScope scope(masm, StackFrame::INTERNAL);
+      __ CallRuntime(Runtime::kThrowDerivedConstructorReturnedNonObject);
+    }
+    __ bind(&dont_throw);
+  }
+
   // Remove caller arguments from the stack and return.
   __ PopReturnAddressTo(rcx);
   SmiIndex index = masm->SmiToIndex(rbx, rbx, kPointerSizeLog2);
@@ -371,17 +385,23 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
 
 
 void Builtins::Generate_JSConstructStubGeneric(MacroAssembler* masm) {
-  Generate_JSConstructStubHelper(masm, false, true);
+  Generate_JSConstructStubHelper(masm, false, true, false);
 }
 
 
 void Builtins::Generate_JSConstructStubApi(MacroAssembler* masm) {
-  Generate_JSConstructStubHelper(masm, true, true);
+  Generate_JSConstructStubHelper(masm, true, true, false);
 }
 
 
 void Builtins::Generate_JSBuiltinsConstructStub(MacroAssembler* masm) {
-  Generate_JSConstructStubHelper(masm, false, false);
+  Generate_JSConstructStubHelper(masm, false, false, false);
+}
+
+
+void Builtins::Generate_JSBuiltinsConstructStubForDerived(
+    MacroAssembler* masm) {
+  Generate_JSConstructStubHelper(masm, false, false, true);
 }