Revert change 5989, which causes failures in some benchmarks.

src/arm/lithium-arm.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 1336 matching lines @@
   switch (op) {
     case kMathAbs:
       return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
     case kMathFloor:
       return AssignEnvironment(DefineAsRegister(result));
     case kMathSqrt:
       return DefineSameAsFirst(result);
     case kMathPowHalf:
       Abort("MathPowHalf LUnaryMathOperation not implemented");
       return NULL;
-    case kMathLog:
-      Abort("MathLog LUnaryMathOperation not implemented");
-      return NULL;
     default:
       UNREACHABLE();
       return NULL;
   }
 }
 
 
 LInstruction* LChunkBuilder::DoCallKeyed(HCallKeyed* instr) {
   ASSERT(instr->key()->representation().IsTagged());
   argument_count_ -= instr->argument_count();
@@ skipping 710 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