[es6] Perform the IsConstructor test in GetSuperConstructor.

src/code-stub-assembler.h

Index: src/code-stub-assembler.h
diff --git a/src/code-stub-assembler.h b/src/code-stub-assembler.h
index 7451f1ffcc916c757dd482c8b17a25c2534a5edc..ac7a83d47c948b0d29206a747ef462cda5906dd9 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -600,6 +600,8 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
   Node* IsHashTable(Node* object);
   Node* IsDictionary(Node* object);
   Node* IsUnseededNumberDictionary(Node* object);
+  Node* IsConstructorMap(Node* map);
+  Node* IsJSFunction(Node* object);
 
   // ElementsKind helpers:
   Node* IsFastElementsKind(Node* elements_kind);
@@ -1014,6 +1016,8 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
 
   Node* Typeof(Node* value, Node* context);
 
+  Node* GetSuperConstructor(Node* value, Node* context);
+
   Node* InstanceOf(Node* object, Node* callable, Node* context);
 
   // Debug helpers