Fix arm port of tracking field representations. Based on Rodolph Perfetta's comments

src/arm/lithium-codegen-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 3067 matching lines @@
   __ bind(&skip_assignment);
 }
 
 
 void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
   Register object = ToRegister(instr->object());
   if (!FLAG_track_double_fields) {
     ASSERT(!instr->hydrogen()->representation().IsDouble());
   }
   Register temp = instr->hydrogen()->representation().IsDouble()
-      ? ToRegister(instr->temp()) : ToRegister(instr->result());
+      ? scratch0() : ToRegister(instr->result());
   if (instr->hydrogen()->is_in_object()) {
     __ ldr(temp, FieldMemOperand(object, instr->hydrogen()->offset()));
   } else {
     __ ldr(temp, FieldMemOperand(object, JSObject::kPropertiesOffset));
     __ ldr(temp, FieldMemOperand(temp, instr->hydrogen()->offset()));
   }
 
   if (instr->hydrogen()->representation().IsDouble()) {
     Label load_from_heap_number, done;
     DwVfpRegister result = ToDoubleRegister(instr->result());
     SwVfpRegister flt_scratch = double_scratch0().low();
     __ JumpIfNotSmi(temp, &load_from_heap_number);
     __ SmiUntag(temp);
     __ vmov(flt_scratch, temp);
     __ vcvt_f64_s32(result, flt_scratch);
     __ b(&done);
-    __ sub(ip, temp, Operand(kHeapObjectTag));
-    __ vldr(result, ip, HeapNumber::kValueOffset);
+    __ bind(&load_from_heap_number);
+    __ vldr(result, FieldMemOperand(temp, HeapNumber::kValueOffset));
     __ bind(&done);
   }
 }
 
 
 void LCodeGen::EmitLoadFieldOrConstantFunction(Register result,
                                                Register object,
                                                Handle<Map> type,
                                                Handle<String> name,
                                                LEnvironment* env) {
@@ skipping 2947 matching lines @@
   __ sub(scratch, result, Operand(index, LSL, kPointerSizeLog2 - kSmiTagSize));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal