Use CommonNodeCache for heap constants in ChangeLowering.

src/compiler/change-lowering.cc

Index: src/compiler/change-lowering.cc
diff --git a/src/compiler/change-lowering.cc b/src/compiler/change-lowering.cc
index 3f8e45b9e71d70b63cde34c37b986999486ab000..8f3be185935aa0953c9f4de2d6511de36840b8a1 100644
--- a/src/compiler/change-lowering.cc
+++ b/src/compiler/change-lowering.cc
@@ -34,8 +34,11 @@ Node* ChangeLoweringBase::ExternalConstant(ExternalReference reference) {
 
 
 Node* ChangeLoweringBase::HeapConstant(PrintableUnique<HeapObject> value) {
-  // TODO(bmeurer): Use common node cache.
-  return graph()->NewNode(common()->HeapConstant(value));
+  Node** loc = cache()->FindHeapConstant(value);
+  if (*loc == NULL) {
+    *loc = graph()->NewNode(common()->HeapConstant(value));
+  }
+  return *loc;
 }