Revert change 5989, which causes failures in some benchmarks.

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
===================================================================
--- src/ia32/lithium-ia32.cc	(revision 5989)
+++ src/ia32/lithium-ia32.cc	(working copy)
@@ -1355,28 +1355,22 @@
 
 LInstruction* LChunkBuilder::DoUnaryMathOperation(HUnaryMathOperation* instr) {
   MathFunctionId op = instr->op();
-  if (op == kMathLog) {
-    LOperand* input = UseFixedDouble(instr->value(), xmm1);
-    LInstruction* result = new LUnaryMathOperation(input);
-    return MarkAsCall(DefineFixedDouble(result, xmm1), instr);
-  } else {
-    LOperand* input = UseRegisterAtStart(instr->value());
-    LInstruction* result = new LUnaryMathOperation(input);
-    switch (op) {
-      case kMathAbs:
-        return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
-      case kMathFloor:
-        return AssignEnvironment(DefineAsRegister(result));
-      case kMathRound:
-        return AssignEnvironment(DefineAsRegister(result));
-      case kMathSqrt:
-        return DefineSameAsFirst(result);
-      case kMathPowHalf:
-        return AssignEnvironment(DefineSameAsFirst(result));
-      default:
-        UNREACHABLE();
-        return NULL;
-    }
+  LOperand* input = UseRegisterAtStart(instr->value());
+  LInstruction* result = new LUnaryMathOperation(input);
+  switch (op) {
+    case kMathAbs:
+      return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
+    case kMathFloor:
+      return AssignEnvironment(DefineAsRegister(result));
+    case kMathRound:
+      return AssignEnvironment(DefineAsRegister(result));
+    case kMathSqrt:
+      return DefineSameAsFirst(result);
+    case kMathPowHalf:
+      return AssignEnvironment(DefineSameAsFirst(result));
+    default:
+      UNREACHABLE();
+      return NULL;
   }
 }