Revert "Track field types."

src/arm64/lithium-codegen-arm64.cc

 // Copyright 2013 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 5247 matching lines @@
   SmiCheck check_needed = instr->hydrogen()->value()->IsHeapObject()
       ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
 
   ASSERT(!(representation.IsSmi() &&
            instr->value()->IsConstantOperand() &&
            !IsInteger32Constant(LConstantOperand::cast(instr->value()))));
   if (representation.IsHeapObject() &&
       !instr->hydrogen()->value()->type().IsHeapObject()) {
     DeoptimizeIfSmi(value, instr->environment());
 
-    // We know now that value is not a smi, so we can omit the check below.
+    // We know that value is a smi now, so we can omit the check below.
     check_needed = OMIT_SMI_CHECK;
   }
 
   if (!transition.is_null()) {
     // Store the new map value.
     Register new_map_value = ToRegister(instr->temp0());
     __ Mov(new_map_value, Operand(transition));
     __ Str(new_map_value, FieldMemOperand(object, HeapObject::kMapOffset));
     if (instr->hydrogen()->NeedsWriteBarrierForMap()) {
       // Update the write barrier for the map field.
@@ skipping 648 matching lines @@
   __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
   // Index is equal to negated out of object property index plus 1.
   __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ Bind(deferred->exit());
   __ Bind(&done);
 }
 
 } }  // namespace v8::internal