Made Isolate a mandatory parameter for everything Handle-related.

src/hydrogen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 232 matching lines @@
   HBasicBlock* loop_header_;
   ZoneList<HBasicBlock*> blocks_;
   HStackCheck* stack_check_;
 };
 
 class BoundsCheckTable;
 class HGraph: public ZoneObject {
  public:
   explicit HGraph(CompilationInfo* info);
 
-  Isolate* isolate() { return isolate_; }
+  Isolate* isolate() const { 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_; }
   HBasicBlock* entry_block() const { return entry_block_; }
   HEnvironment* start_environment() const { return start_environment_; }
 
   void InitializeInferredTypes();
   void InsertTypeConversions();
@@ skipping 1401 matching lines @@
   const char* filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_