One Zone per CompilationInfo.

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index bdce3e5f3066cdb5f593f55db2ef4a2a41cd2492..abaa4401b4f7ba8a44a7d40d0182a7331757bf8d 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -244,10 +244,11 @@ class HLoopInformation: public ZoneObject {
 class BoundsCheckTable;
 class HGraph: public ZoneObject {
  public:
-  HGraph(CompilationInfo* info, Zone* zone);
+  explicit HGraph(CompilationInfo* info);
 
   Isolate* isolate() { return isolate_; }
   Zone* zone() const { return zone_; }
+  CompilationInfo* info() const { return info_; }
 
   const ZoneList<HBasicBlock*>* blocks() const { return &blocks_; }
   const ZoneList<HPhi*>* phi_list() const { return phi_list_; }
@@ -280,7 +281,7 @@ class HGraph: public ZoneObject {
 
   void CollectPhis();
 
-  Handle<Code> Compile(CompilationInfo* info, Zone* zone);
+  Handle<Code> Compile();
 
   void set_undefined_constant(HConstant* constant) {
     undefined_constant_.set(constant);
@@ -380,6 +381,7 @@ class HGraph: public ZoneObject {
   SetOncePointer<HBasicBlock> osr_loop_entry_;
   SetOncePointer<ZoneList<HUnknownOSRValue*> > osr_values_;
 
+  CompilationInfo* info_;
   Zone* zone_;
 
   bool is_recursive_;
@@ -830,7 +832,7 @@ class HGraphBuilder: public AstVisitor {
     BreakAndContinueScope* next_;
   };
 
-  HGraphBuilder(CompilationInfo* info, TypeFeedbackOracle* oracle, Zone* zone);
+  HGraphBuilder(CompilationInfo* info, TypeFeedbackOracle* oracle);
 
   HGraph* CreateGraph();