Remove the dependency of Zone on Isolate

src/compiler/typer.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_TYPER_H_
 #define V8_COMPILER_TYPER_H_
 
 #include "src/v8.h"
 
 #include "src/compiler/graph.h"
 #include "src/compiler/opcodes.h"
 #include "src/types.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 class LazyTypeCache;
 
 
 class Typer {
  public:
-  explicit Typer(Graph* graph, MaybeHandle<Context> context);
+  Typer(Isolate* isolate, Graph* graph, MaybeHandle<Context> context);
   ~Typer();
 
   void Run();
 
   Graph* graph() { return graph_; }
   MaybeHandle<Context> context() { return context_; }
   Zone* zone() { return graph_->zone(); }
-  Isolate* isolate() { return zone()->isolate(); }
+  Isolate* isolate() { return isolate_; }
 
  private:
   class Visitor;
   class Decorator;
 
+  Isolate* isolate_;
   Graph* graph_;
   MaybeHandle<Context> context_;
   Decorator* decorator_;
 
   Zone* zone_;
   Type* boolean_or_number;
   Type* undefined_or_null;
   Type* undefined_or_number;
   Type* negative_signed32;
   Type* non_negative_signed32;
@@ skipping 19 matching lines @@
   ZoneVector<Handle<Object> > weaken_min_limits_;
   ZoneVector<Handle<Object> > weaken_max_limits_;
   DISALLOW_COPY_AND_ASSIGN(Typer);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_TYPER_H_