Fix several register allocation issues revealed by fuzzer:

src/ia32/lithium-ia32.cc

 // Copyright 2010 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 1632 matching lines @@
   ASSERT(instr->value()->representation().IsTagged());
   LOperand* value = UseRegisterAtStart(instr->value());
 
   return DefineAsRegister(new LIsNull(value,
                                       instr->is_strict()));
 }
 
 
 LInstruction* LChunkBuilder::DoIsObject(HIsObject* instr) {
   ASSERT(instr->value()->representation().IsTagged());
-  LOperand* value = UseRegisterAtStart(instr->value());
+  LOperand* value = UseRegister(instr->value());
 
   return DefineAsRegister(new LIsObject(value, TempRegister()));
 }
 
 
 LInstruction* LChunkBuilder::DoIsSmi(HIsSmi* instr) {
   ASSERT(instr->value()->representation().IsTagged());
   LOperand* value = UseAtStart(instr->value());
 
   return DefineAsRegister(new LIsSmi(value));
@@ skipping 467 matching lines @@
 void LPointerMap::PrintTo(StringStream* stream) const {
   stream->Add("{");
   for (int i = 0; i < pointer_operands_.length(); ++i) {
     if (i != 0) stream->Add(";");
     pointer_operands_[i]->PrintTo(stream);
   }
   stream->Add("} @%d", position());
 }
 
 } }  // namespace v8::internal