Use the BitField class for Code::Flags.

src/stub-cache.cc

 // Copyright 2011 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 56 matching lines @@
   // Validate that the name does not move on scavenge, and that we
   // can use identity checks instead of string equality checks.
   ASSERT(!heap()->InNewSpace(name));
   ASSERT(name->IsSymbol());
 
   // The state bits are not important to the hash function because
   // the stub cache only contains monomorphic stubs. Make sure that
   // the bits are the least significant so they will be the ones
   // masked out.
   ASSERT(Code::ExtractICStateFromFlags(flags) == MONOMORPHIC);
-  ASSERT(Code::kFlagsICStateShift == 0);
+  STATIC_ASSERT((Code::ICStateField::kMask & 1) == 1);
 
   // Make sure that the code type is not included in the hash.
   ASSERT(Code::ExtractTypeFromFlags(flags) == 0);
 
   // Compute the primary entry.
   int primary_offset = PrimaryOffset(name, flags, map);
   Entry* primary = entry(primary_, primary_offset);
   Code* hit = primary->value;
 
   // If the primary entry has useful data in it, we retire it to the
@@ skipping 1798 matching lines @@
       expected_receiver_type_ =
           FunctionTemplateInfo::cast(signature->receiver());
     }
   }
 
   is_simple_api_call_ = true;
 }
 
 
 } }  // namespace v8::internal