[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 19ccf7f084cbdd016d02b2c3f7b74f25b48cdd33..d93d60edc9ed6ffe65132bdbabdfc1c509160233 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -658,6 +658,8 @@ 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);
@@ -1078,6 +1080,8 @@ 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