[es2015] Simplify contract between parser and stub for derived constructors.

src/builtins/x64/builtins-x64.cc

Index: src/builtins/x64/builtins-x64.cc
diff --git a/src/builtins/x64/builtins-x64.cc b/src/builtins/x64/builtins-x64.cc
index 35bef25b61a43e54174c287a4fdb21ed654988fa..51f734567bdb702bf4818cf3d68e2ed8b5594ca4 100644
--- a/src/builtins/x64/builtins-x64.cc
+++ b/src/builtins/x64/builtins-x64.cc
@@ -226,11 +226,15 @@ void Generate_JSConstructStubHelper(MacroAssembler* masm, bool is_api_function,
   }
 
   // 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.
+  // For derived class constructors, throw a TypeError here if the result
+  // is not a JSReceiver.
   if (check_derived_construct) {
-    Label dont_throw;
-    __ JumpIfNotSmi(rax, &dont_throw);
+    Label do_throw, dont_throw;
+    __ JumpIfSmi(rax, &do_throw, Label::kNear);
+    STATIC_ASSERT(LAST_JS_RECEIVER_TYPE == LAST_TYPE);
+    __ CmpObjectType(rax, FIRST_JS_RECEIVER_TYPE, rcx);
+    __ j(above_equal, &dont_throw, Label::kNear);
+    __ bind(&do_throw);
     {
       FrameScope scope(masm, StackFrame::INTERNAL);
       __ CallRuntime(Runtime::kThrowDerivedConstructorReturnedNonObject);