X87: [builtins] Introduce proper Float64Exp operator.

src/x87/codegen-x87.cc

Index: src/x87/codegen-x87.cc
diff --git a/src/x87/codegen-x87.cc b/src/x87/codegen-x87.cc
index d302841fa1046dcac086cafd03597d96078680f9..5cda23dcea35c7fea74adcf9c3d2070392a022a8 100644
--- a/src/x87/codegen-x87.cc
+++ b/src/x87/codegen-x87.cc
@@ -33,10 +33,6 @@ void StubRuntimeCallHelper::AfterCall(MacroAssembler* masm) const {
 
 #define __ masm.
 
-UnaryMathFunctionWithIsolate CreateExpFunction(Isolate* isolate) {
-  return nullptr;
-}
-
 
 UnaryMathFunctionWithIsolate CreateSqrtFunction(Isolate* isolate) {
   size_t actual_size;