[builtins] Introduce proper Float64Exp operator.

src/crankshaft/arm64/lithium-arm64.cc

Index: src/crankshaft/arm64/lithium-arm64.cc
diff --git a/src/crankshaft/arm64/lithium-arm64.cc b/src/crankshaft/arm64/lithium-arm64.cc
index d00bc17d4734f77ee822de10c8f66e4d4c0729a7..e18fca528b165e8aee6bc5ad224d53a76f6a59e7 100644
--- a/src/crankshaft/arm64/lithium-arm64.cc
+++ b/src/crankshaft/arm64/lithium-arm64.cc
@@ -2462,14 +2462,9 @@ LInstruction* LChunkBuilder::DoUnaryMathOperation(HUnaryMathOperation* instr) {
     case kMathExp: {
       DCHECK(instr->representation().IsDouble());
       DCHECK(instr->value()->representation().IsDouble());
-      LOperand* input = UseRegister(instr->value());
-      LOperand* double_temp1 = TempDoubleRegister();
-      LOperand* temp1 = TempRegister();
-      LOperand* temp2 = TempRegister();
-      LOperand* temp3 = TempRegister();
-      LMathExp* result = new(zone()) LMathExp(input, double_temp1,
-                                              temp1, temp2, temp3);
-      return DefineAsRegister(result);
+      LOperand* input = UseFixedDouble(instr->value(), d0);
+      LMathExp* result = new (zone()) LMathExp(input);
+      return MarkAsCall(DefineFixedDouble(result, d0), instr);
     }
     case kMathFloor: {
       DCHECK(instr->value()->representation().IsDouble());