Revert r4782. Fix issues 728, 732.

src/x64/ic-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 424 matching lines @@
 
   __ bind(&check_string);
   // The key is not a smi.
   // Is it a string?
   // rdx: receiver
   // rax: key
   __ CmpObjectType(rax, FIRST_NONSTRING_TYPE, rcx);
   __ j(above_equal, &slow);
   // Is the string an array index, with cached numeric value?
   __ movl(rbx, FieldOperand(rax, String::kHashFieldOffset));
-  __ testl(rbx, Immediate(String::kIsArrayIndexMask));
-  __ j(not_zero, &index_string);  // The value in rbx is used at jump target.
+  __ testl(rbx, Immediate(String::kContainsCachedArrayIndexMask));
+  __ j(zero, &index_string);  // The value in rbx is used at jump target.
 
   // Is the string a symbol?
   ASSERT(kSymbolTag != 0);
   __ testb(FieldOperand(rcx, Map::kInstanceTypeOffset),
            Immediate(kIsSymbolMask));
   __ j(zero, &slow);
 
   // If the receiver is a fast-case object, check the keyed lookup
   // cache. Otherwise probe the dictionary leaving result in rcx.
   __ movq(rbx, FieldOperand(rdx, JSObject::kPropertiesOffset));
@@ skipping 1124 matching lines @@
   GenerateMiss(masm);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64