MIPS: Fix PrepareKeyedOperand on MIPS.

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.7
 // 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 3241 matching lines @@
     return MemOperand(base,
                       base_offset + (constant_key << element_size));
   }
 
   if (additional_offset != 0) {
     if (shift_size >= 0) {
       __ sll(scratch0(), key, shift_size);
       __ Addu(scratch0(), scratch0(), Operand(base_offset));
     } else {
       ASSERT_EQ(-1, shift_size);
-      __ srl(scratch0(), key, 1);
+      // Key can be negative, so using sra here.
+      __ sra(scratch0(), key, 1);
       __ Addu(scratch0(), scratch0(), Operand(base_offset));
     }
     __ Addu(scratch0(), base, scratch0());
     return MemOperand(scratch0());
   }
 
   if (additional_index != 0) {
     additional_index *= 1 << (element_size - shift_size);
     __ Addu(scratch0(), key, Operand(additional_index));
   }
@@ skipping 2541 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal