[wasm] Add utilities to print out WASM ast directly from the bytes.

src/wasm/ast-decoder.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_WASM_AST_DECODER_H_
 #define V8_WASM_AST_DECODER_H_
 
 #include "src/signature.h"
 #include "src/wasm/wasm-opcodes.h"
 #include "src/wasm/wasm-result.h"
@@ skipping 71 matching lines @@
 struct Tree;
 typedef Result<Tree*> TreeResult;
 
 std::ostream& operator<<(std::ostream& os, const Tree& tree);
 
 TreeResult VerifyWasmCode(FunctionEnv* env, const byte* base, const byte* start,
                           const byte* end);
 TreeResult BuildTFGraph(TFBuilder* builder, FunctionEnv* env, const byte* base,
                         const byte* start, const byte* end);
 
+void PrintAst(FunctionEnv* env, const byte* start, const byte* end);
+
 inline TreeResult VerifyWasmCode(FunctionEnv* env, const byte* start,
                                  const byte* end) {
   return VerifyWasmCode(env, nullptr, start, end);
 }
 
 inline TreeResult BuildTFGraph(TFBuilder* builder, FunctionEnv* env,
                                const byte* start, const byte* end) {
   return BuildTFGraph(builder, env, nullptr, start, end);
 }
 
 enum ReadUnsignedLEB128ErrorCode { kNoError, kInvalidLEB128, kMissingLEB128 };
 
 ReadUnsignedLEB128ErrorCode ReadUnsignedLEB128Operand(const byte*, const byte*,
                                                       int*, uint32_t*);
 
 // Computes the length of the opcode at the given address.
 int OpcodeLength(const byte* pc);
 
 // Computes the arity (number of sub-nodes) of the opcode at the given address.
 int OpcodeArity(FunctionEnv* env, const byte* pc);
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_AST_DECODER_H_