Revert of [builtins] Introduce proper Float64Exp operator.

src/crankshaft/x64/lithium-x64.cc

Index: src/crankshaft/x64/lithium-x64.cc
diff --git a/src/crankshaft/x64/lithium-x64.cc b/src/crankshaft/x64/lithium-x64.cc
index 192c3beac9a37202fe3b20189ca3240a308155dd..22d8ac5b7733a2026fcca17acdacc8ffefb15e19 100644
--- a/src/crankshaft/x64/lithium-x64.cc
+++ b/src/crankshaft/x64/lithium-x64.cc
@@ -1171,9 +1171,11 @@
 LInstruction* LChunkBuilder::DoMathExp(HUnaryMathOperation* instr) {
   DCHECK(instr->representation().IsDouble());
   DCHECK(instr->value()->representation().IsDouble());
-  LOperand* input = UseFixedDouble(instr->value(), xmm0);
-  return MarkAsCall(DefineFixedDouble(new (zone()) LMathExp(input), xmm0),
-                    instr);
+  LOperand* value = UseTempRegister(instr->value());
+  LOperand* temp1 = TempRegister();
+  LOperand* temp2 = TempRegister();
+  LMathExp* result = new(zone()) LMathExp(value, temp1, temp2);
+  return DefineAsRegister(result);
 }