Fix ARM bug introduced in r12604 that caused crashes on ARM

src/arm/macro-assembler-arm.cc

 // Copyright 2012 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 1970 matching lines @@
       Operand(key_reg, LSL, kDoubleSizeLog2 - kSmiTagSize));
   // scratch1 is now effective address of the double element
 
   FloatingPointHelper::Destination destination;
   if (CpuFeatures::IsSupported(VFP2)) {
     destination = FloatingPointHelper::kVFPRegisters;
   } else {
     destination = FloatingPointHelper::kCoreRegisters;
   }
 
-  Register untagged_value = receiver_reg;
+  Register untagged_value = elements_reg;
   SmiUntag(untagged_value, value_reg);
   FloatingPointHelper::ConvertIntToDouble(this,
                                           untagged_value,
                                           destination,
                                           d0,
                                           mantissa_reg,
                                           exponent_reg,
                                           scratch4,
                                           s2);
   if (destination == FloatingPointHelper::kVFPRegisters) {
@@ skipping 1837 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM