Add support for enabling DCHECKs in release mode

src/compiler/ast-graph-builder.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_AST_GRAPH_BUILDER_H_
 #define V8_COMPILER_AST_GRAPH_BUILDER_H_
 
 #include "src/v8.h"
 
 #include "src/ast.h"
@@ skipping 312 matching lines @@
 
  protected:
   AstContext(AstGraphBuilder* owner, Expression::Context kind);
   virtual ~AstContext();
 
   AstGraphBuilder* owner() const { return owner_; }
   Environment* environment() const { return owner_->environment(); }
 
 // We want to be able to assert, in a context-specific way, that the stack
 // height makes sense when the context is filled.
-#ifdef DEBUG
+#if DCHECK_IS_ON
   int original_height_;
 #endif
 
  private:
   Expression::Context kind_;
   AstGraphBuilder* owner_;
   AstContext* outer_;
 };
 
 
@@ skipping 97 matching lines @@
 
 Scope* AstGraphBuilder::current_scope() const {
   return execution_context_->scope();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_AST_GRAPH_BUILDER_H_