Improve handling of property loads on the proto chain.

src/mips/lithium-codegen-mips.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 4619 matching lines @@
   __ jmp(&done);
 
   __ bind(&is_smi);
   __ ClampUint8(result_reg, scratch);
 
   __ bind(&done);
 }
 
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
+  ASSERT(instr->temp()->Equals(instr->result()));
   Register temp1 = ToRegister(instr->temp());
   Register temp2 = ToRegister(instr->temp2());
 
   Handle<JSObject> holder = instr->holder();
   Handle<JSObject> current_prototype = instr->prototype();
 
   // Load prototype object.
   __ LoadHeapObject(temp1, current_prototype);
 
   // Check prototype maps up to the holder.
@@ skipping 789 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal