[turbofan] Move SimplifiedOperatorBuilder into JSGraph.

src/compiler/js-global-specialization.cc

Index: src/compiler/js-global-specialization.cc
diff --git a/src/compiler/js-global-specialization.cc b/src/compiler/js-global-specialization.cc
index 9b11767be6c4c7eb342a17ab34e02ba705bf4be8..372cd72f8622bed434047ee6f1b8e21b1b713f62 100644
--- a/src/compiler/js-global-specialization.cc
+++ b/src/compiler/js-global-specialization.cc
@@ -30,8 +30,7 @@ JSGlobalSpecialization::JSGlobalSpecialization(
       jsgraph_(jsgraph),
       flags_(flags),
       global_object_(global_object),
-      dependencies_(dependencies),
-      simplified_(graph()->zone()) {}
+      dependencies_(dependencies) {}
 
 
 Reduction JSGlobalSpecialization::Reduce(Node* node) {
@@ -277,6 +276,11 @@ JSOperatorBuilder* JSGlobalSpecialization::javascript() const {
   return jsgraph()->javascript();
 }
 
+
+SimplifiedOperatorBuilder* JSGlobalSpecialization::simplified() const {
+  return jsgraph()->simplified();
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8