[wasm] Cleanup AST decoder. Remove Tree and TreeResult.

src/wasm/module-decoder.cc

 // 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.
 
 #include "src/wasm/module-decoder.h"
 
 #include "src/base/functional.h"
 #include "src/base/platform/platform.h"
 #include "src/macro-assembler.h"
 #include "src/objects.h"
@@ skipping 528 matching lines @@
   void VerifyFunctionBody(uint32_t func_num, ModuleEnv* menv,
                           WasmFunction* function) {
     if (FLAG_trace_wasm_decoder || FLAG_trace_wasm_decode_time) {
       OFStream os(stdout);
       os << "Verifying WASM function " << WasmFunctionName(function, menv)
          << std::endl;
     }
     FunctionBody body = {menv, function->sig, start_,
                          start_ + function->code_start_offset,
                          start_ + function->code_end_offset};
-    TreeResult result = VerifyWasmCode(module_zone->allocator(), body);
+    DecodeResult result = VerifyWasmCode(module_zone->allocator(), body);
     if (result.failed()) {
       // Wrap the error message from the function decoder.
       std::ostringstream str;
       str << "in function " << WasmFunctionName(function, menv) << ": ";
       str << result;
       std::string strval = str.str();
       const char* raw = strval.c_str();
       size_t len = strlen(raw);
       char* buffer = new char[len];
       strncpy(buffer, raw, len);
@@ skipping 279 matching lines @@
     decoder.consume_bytes(size);
   }
   if (decoder.more()) decoder.error("unexpected additional bytes");
 
   return decoder.toResult(std::move(table));
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8