Patch 2.1 branch with bug fix change 4471.

src/x64/codegen-x64.cc

 // Copyright 2010 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 5333 matching lines @@
     case Token::BIT_AND:
       // Result is always a smi.
       result_type = TypeInfo::Smi();
       break;
     case Token::SAR:
     case Token::SHL:
       // Result is always a smi.
       result_type = TypeInfo::Smi();
       break;
     case Token::SHR:
-      // Result of x >>> y is always a smi if y >= 1, otherwise a number.
+      // Result of x >>> y is always a smi if masked y >= 1, otherwise a number.
       result_type = (right.is_constant() && right.handle()->IsSmi()
-                     && Smi::cast(*right.handle())->value() >= 1)
+                     && (Smi::cast(*right.handle())->value() & 0x1F) >= 1)
           ? TypeInfo::Smi()
           : TypeInfo::Number();
       break;
     case Token::ADD:
       // Result could be a string or a number. Check types of inputs.
       result_type = operands_type.IsNumber()
           ? TypeInfo::Number()
           : TypeInfo::Unknown();
       break;
     case Token::SUB:
@@ skipping 4626 matching lines @@
   // Call the function from C++.
   return FUNCTION_CAST<ModuloFunction>(buffer);
 }
 
 #endif
 
 
 #undef __
 
 } }  // namespace v8::internal