[turbofan] Do constant folding for Float64Pow.

src/wasm/wasm-external-refs.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <math.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <limits>
 
 #include "include/v8config.h"
@@ skipping 188 matching lines @@
   return static_cast<uint32_t>(base::bits::CountPopulation(*input));
 }
 
 uint32_t word64_popcnt_wrapper(uint64_t* input) {
   return static_cast<uint32_t>(base::bits::CountPopulation(*input));
 }
 
 void float64_pow_wrapper(double* param0, double* param1) {
   double x = ReadDoubleValue(param0);
   double y = ReadDoubleValue(param1);
-  if (std::isnan(y) || ((x == 1 || x == -1) && std::isinf(y))) {
-    WriteDoubleValue(param0, std::numeric_limits<double>::quiet_NaN());
-  }
   WriteDoubleValue(param0, Pow(x, y));
 }
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8