Disable tracking of double fields during snapshot creation.

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 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 2797 matching lines @@
       ASSERT(result.is(rax));
       __ load_rax(ToExternalReference(LConstantOperand::cast(instr->object())));
     } else {
       Register object = ToRegister(instr->object());
       __ Load(result, MemOperand(object, offset), access.representation());
     }
     return;
   }
 
   Register object = ToRegister(instr->object());
-  if (FLAG_track_double_fields &&
-      instr->hydrogen()->representation().IsDouble()) {
+  if (instr->hydrogen()->representation().IsDouble()) {
     XMMRegister result = ToDoubleRegister(instr->result());
     __ movsd(result, FieldOperand(object, offset));
     return;
   }
 
   Register result = ToRegister(instr->result());
   if (!access.IsInobject()) {
     __ movp(result, FieldOperand(object, JSObject::kPropertiesOffset));
     object = result;
   }
@@ skipping 1130 matching lines @@
       if (IsInteger32Constant(operand_value)) {
         DeoptimizeIf(no_condition, instr->environment());
       }
     } else {
       if (!hinstr->value()->type().IsHeapObject()) {
         Register value = ToRegister(instr->value());
         Condition cc = masm()->CheckSmi(value);
         DeoptimizeIf(cc, instr->environment());
       }
     }
-  } else if (FLAG_track_double_fields && representation.IsDouble()) {
+  } else if (representation.IsDouble()) {
     ASSERT(transition.is_null());
     ASSERT(access.IsInobject());
     ASSERT(!hinstr->NeedsWriteBarrier());
     XMMRegister value = ToDoubleRegister(instr->value());
     __ movsd(FieldOperand(object, offset), value);
     return;
   }
 
   if (!transition.is_null()) {
     if (!hinstr->NeedsWriteBarrierForMap()) {
@@ skipping 1642 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64