[es6] Perform the IsConstructor test in GetSuperConstructor.

src/code-stub-assembler.cc

Index: src/code-stub-assembler.cc
diff --git a/src/code-stub-assembler.cc b/src/code-stub-assembler.cc
index 1a1ce3944396390e35c23fdf530f27bff9f656d5..6a1641ea91890478f85355705dd808fab120da77 100644
--- a/src/code-stub-assembler.cc
+++ b/src/code-stub-assembler.cc
@@ -7816,6 +7816,26 @@ compiler::Node* CodeStubAssembler::Typeof(compiler::Node* value,
   return result_var.value();
 }
 
+compiler::Node* CodeStubAssembler::GetSuperConstructor(
+    compiler::Node* active_function, compiler::Node* context) {
+  Node* map = LoadMap(active_function);

[caitp, 2016/11/21 13:52:53]

I would add a CSA_ASSERT() to ensure that this is a HeapObject

[Benedikt Meurer, 2016/11/23 04:51:00]

Yes, please.

[Henrique Ferreiro, 2016/12/01 12:22:22]

Similar code checks for a Smi and a HeapNumber, is the latter neccessary? I
would assume a heap number also has a map.

+  Node* prototype = LoadMapPrototype(map);
+  Node* bit_field = LoadMapBitField(map);
+
+  Label not_constructor(this);

[caitp, 2016/11/21 13:52:53]

You want this label to be deferred.

[Henrique Ferreiro, 2016/12/01 12:22:22]

Would you mind explaining what is that for?

+  GotoUnless(
+      Word32Equal(Word32And(bit_field, Int32Constant(1 << Map::kIsConstructor)),
+                  Int32Constant(1 << Map::kIsConstructor)),
+      &not_constructor);
+  return prototype;
+
+  Bind(&not_constructor);
+  {
+    CallRuntime(Runtime::kThrowConstructedNonConstructable, active_function);
+    return UndefinedConstant();  // Never reached.
+  }
+}
+
 compiler::Node* CodeStubAssembler::InstanceOf(compiler::Node* object,
                                               compiler::Node* callable,
                                               compiler::Node* context) {