[turbofan] Avoid unnecessary copying of nodes during inlining.

src/compiler/js-graph.h

Index: src/compiler/js-graph.h
diff --git a/src/compiler/js-graph.h b/src/compiler/js-graph.h
index e772da8c30f8873552332c64907e52413cef1b40..3dacc35e3cbdaec74701b6319f86737a947f7f2c 100644
--- a/src/compiler/js-graph.h
+++ b/src/compiler/js-graph.h
@@ -127,6 +127,10 @@ class JSGraph : public ZoneObject {
   // cannot deopt.
   Node* EmptyFrameState();
 
+  // Creates an empty StateValues node, used when we don't have any concrete
+  // values for a certain part of the frame state.
+  Node* EmptyStateValues();
+
   // Create a control node that serves as dependency for dead nodes.
   Node* Dead();
 
@@ -159,6 +163,7 @@ class JSGraph : public ZoneObject {
     kOneConstant,
     kNaNConstant,
     kEmptyFrameState,
+    kEmptyStateValues,
     kDead,
     kNumCachedNodes  // Must remain last.
   };