Revert of [builtins] Introduce proper Float64Exp operator.

src/arm64/codegen-arm64.h

Index: src/arm64/codegen-arm64.h
diff --git a/src/arm64/codegen-arm64.h b/src/arm64/codegen-arm64.h
index b0490a8a03366bbefa5a3e623cbc6515e9b9d772..573f6fe159c4586fb74700b832ef212cb801f3f0 100644
--- a/src/arm64/codegen-arm64.h
+++ b/src/arm64/codegen-arm64.h
@@ -27,6 +27,22 @@
   DISALLOW_COPY_AND_ASSIGN(StringCharLoadGenerator);
 };
 
+
+class MathExpGenerator : public AllStatic {
+ public:
+  static void EmitMathExp(MacroAssembler* masm,
+                          DoubleRegister input,
+                          DoubleRegister result,
+                          DoubleRegister double_scratch1,
+                          DoubleRegister double_scratch2,
+                          Register temp1,
+                          Register temp2,
+                          Register temp3);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MathExpGenerator);
+};
+
 }  // namespace internal
 }  // namespace v8