[turbofan] Initial support for monomorphic/polymorphic property loads.

src/compiler/js-graph.cc

Index: src/compiler/js-graph.cc
diff --git a/src/compiler/js-graph.cc b/src/compiler/js-graph.cc
index 9b6b187c6aab2bf203e43e5a3b478680e794678d..9db67b5f7c30126ee940e2f885ab0feb4bd087f3 100644
--- a/src/compiler/js-graph.cc
+++ b/src/compiler/js-graph.cc
@@ -11,8 +11,11 @@ namespace v8 {
 namespace internal {
 namespace compiler {
 
-Node* JSGraph::ImmovableHeapConstant(Handle<HeapObject> object) {
-  return graph()->NewNode(common()->HeapConstant(object));
+Node* JSGraph::ImmovableHeapConstant(Handle<HeapObject> value) {
+  if (value->IsConsString()) {
+    value = String::Flatten(Handle<String>::cast(value), TENURED);
+  }
+  return graph()->NewNode(common()->HeapConstant(value));
 }
 
 
@@ -78,7 +81,7 @@ Node* JSGraph::HeapConstant(Handle<HeapObject> value) {
   // TODO(titzer): We could also match against the addresses of immortable
   // immovables here, even without access to the heap, thus always
   // canonicalizing references to them.
-  return graph()->NewNode(common()->HeapConstant(value));
+  return ImmovableHeapConstant(value);
 }