[turbofan] First steps towards optimizing for-in loops.

src/compiler/graph.h

Index: src/compiler/graph.h
diff --git a/src/compiler/graph.h b/src/compiler/graph.h
index d71bb84ac7fcce3f78b46a656da43fa018f1ce10..0b1277ca1dcb1ff0d16d3edafc40bffffc214d28 100644
--- a/src/compiler/graph.h
+++ b/src/compiler/graph.h
@@ -74,6 +74,11 @@ class Graph : public ZoneObject {
     Node* nodes[] = {n1, n2, n3, n4, n5, n6, n7, n8};
     return NewNode(op, arraysize(nodes), nodes);
   }
+  Node* NewNode(const Operator* op, Node* n1, Node* n2, Node* n3, Node* n4,
+                Node* n5, Node* n6, Node* n7, Node* n8, Node* n9) {
+    Node* nodes[] = {n1, n2, n3, n4, n5, n6, n7, n8, n9};
+    return NewNode(op, arraysize(nodes), nodes);
+  }
 
   template <class Visitor>
   inline void VisitNodeInputsFromEnd(Visitor* visitor);