Add support for enabling DCHECKs in release mode

src/assembler.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 154 matching lines @@
   AssemblerBase* assembler_;
   int expected_size_;
   int start_offset_;
   bool old_value_;
 };
 
 
 // Enable a specified feature within a scope.
 class CpuFeatureScope BASE_EMBEDDED {
  public:
-#ifdef DEBUG
+#if DCHECK_IS_ON
   CpuFeatureScope(AssemblerBase* assembler, CpuFeature f);
   ~CpuFeatureScope();
 
  private:
   AssemblerBase* assembler_;
   uint64_t old_enabled_;
 #else
   CpuFeatureScope(AssemblerBase* assembler, CpuFeature f) {}
 #endif
 };
@@ skipping 403 matching lines @@
   void PatchCodeWithCall(Address target, int guard_bytes);
 
   // Check whether this return sequence has been patched
   // with a call to the debugger.
   INLINE(bool IsPatchedReturnSequence());
 
   // Check whether this debug break slot has been patched with a call to the
   // debugger.
   INLINE(bool IsPatchedDebugBreakSlotSequence());
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
   // Check whether the given code contains relocation information that
   // either is position-relative or movable by the garbage collector.
   static bool RequiresRelocation(const CodeDesc& desc);
 #endif
 
 #ifdef ENABLE_DISASSEMBLER
   // Printing
   static const char* RelocModeName(Mode rmode);
   void Print(Isolate* isolate, std::ostream& os);  // NOLINT
 #endif  // ENABLE_DISASSEMBLER
@@ skipping 520 matching lines @@
   NullCallWrapper() { }
   virtual ~NullCallWrapper() { }
   virtual void BeforeCall(int call_size) const { }
   virtual void AfterCall() const { }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_