[wasm] Fix more -Wsign-compare warnings.

src/wasm/ast-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/signature.h"
 
 #include "src/bit-vector.h"
 #include "src/flags.h"
 #include "src/handles.h"
 #include "src/zone/zone-containers.h"
@@ skipping 556 matching lines @@
     for (int i = 0; i < kMaxIndent; ++i) bytes[i] = ' ';
     bytes[kMaxIndent] = 0;
     if (stack_.size() < kMaxIndent / 2) {
       bytes[stack_.size() * 2] = 0;
     }
     return bytes;
   }
 
   // Decodes the locals declarations, if any, populating {local_type_vec_}.
   void DecodeLocalDecls() {
-    DCHECK_EQ(0, local_type_vec_.size());
+    DCHECK_EQ(0u, local_type_vec_.size());
     // Initialize {local_type_vec} from signature.
     if (sig_) {
       local_type_vec_.reserve(sig_->parameter_count());
       for (size_t i = 0; i < sig_->parameter_count(); ++i) {
         local_type_vec_.push_back(sig_->GetParam(i));
       }
     }
     // Decode local declarations, if any.
     uint32_t entries = consume_u32v("local decls count");
     TRACE("local decls count: %u\n", entries);
@@ skipping 1447 matching lines @@
 BitVector* AnalyzeLoopAssignmentForTesting(Zone* zone, size_t num_locals,
                                            const byte* start, const byte* end) {
   FunctionBody body = {nullptr, nullptr, nullptr, start, end};
   WasmFullDecoder decoder(zone, nullptr, body);
   return decoder.AnalyzeLoopAssignmentForTesting(start, num_locals);
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8