[builtins] Introduce proper Float64Exp operator.

src/crankshaft/arm64/lithium-codegen-arm64.cc

Index: src/crankshaft/arm64/lithium-codegen-arm64.cc
diff --git a/src/crankshaft/arm64/lithium-codegen-arm64.cc b/src/crankshaft/arm64/lithium-codegen-arm64.cc
index 422b7271b4e9b7ecd76dc74cac8e1017361006c6..0754b850297c0ee4595272c772e42fefb71b838f 100644
--- a/src/crankshaft/arm64/lithium-codegen-arm64.cc
+++ b/src/crankshaft/arm64/lithium-codegen-arm64.cc
@@ -3548,17 +3548,10 @@ void LCodeGen::DoMathAbsTagged(LMathAbsTagged* instr) {
 
 
 void LCodeGen::DoMathExp(LMathExp* instr) {
-  DoubleRegister input = ToDoubleRegister(instr->value());
-  DoubleRegister result = ToDoubleRegister(instr->result());
-  DoubleRegister double_temp1 = ToDoubleRegister(instr->double_temp1());
-  DoubleRegister double_temp2 = double_scratch();
-  Register temp1 = ToRegister(instr->temp1());
-  Register temp2 = ToRegister(instr->temp2());
-  Register temp3 = ToRegister(instr->temp3());
-
-  MathExpGenerator::EmitMathExp(masm(), input, result,
-                                double_temp1, double_temp2,
-                                temp1, temp2, temp3);
+  DCHECK(instr->IsMarkedAsCall());
+  DCHECK(ToDoubleRegister(instr->value()).is(d0));
+  __ CallCFunction(ExternalReference::ieee754_exp_function(isolate()), 0, 1);
+  DCHECK(ToDoubleRegister(instr->result()).Is(d0));
 }