[wasm] Use the new Float64Pow TF operator to implement F64Pow.

src/compiler/wasm-compiler.h

 // Copyright 2015 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.
 
 #ifndef V8_COMPILER_WASM_COMPILER_H_
 #define V8_COMPILER_WASM_COMPILER_H_
 
 // Clients of this interface shouldn't depend on lots of compiler internals.
 // Do not include anything from src/compiler here!
 #include "src/compiler.h"
@@ skipping 257 matching lines @@
   Node* BuildF32NearestInt(Node* input);
   Node* BuildF64Trunc(Node* input);
   Node* BuildF64Floor(Node* input);
   Node* BuildF64Ceil(Node* input);
   Node* BuildF64NearestInt(Node* input);
   Node* BuildI32Rol(Node* left, Node* right);
   Node* BuildI64Rol(Node* left, Node* right);
 
   Node* BuildF64Acos(Node* input);
   Node* BuildF64Asin(Node* input);
-  Node* BuildF64Pow(Node* left, Node* right);
   Node* BuildF64Mod(Node* left, Node* right);
 
   Node* BuildIntToFloatConversionInstruction(
       Node* input, ExternalReference ref,
       MachineRepresentation parameter_representation,
       const MachineType result_type);
   Node* BuildF32SConvertI64(Node* input);
   Node* BuildF32UConvertI64(Node* input);
   Node* BuildF64SConvertI64(Node* input);
   Node* BuildF64UConvertI64(Node* input);
@@ skipping 52 matching lines @@
     Node** buf = Buffer(new_count);
     if (buf != buffer) memcpy(buf, buffer, old_count * sizeof(Node*));
     return buf;
   }
 };
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_WASM_COMPILER_H_