[parser, serializer] Fix more -Wsign-compare warnings.

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 6102 matching lines @@
   CHECK(declarations->AtForTest(12)->proxy()->raw_name()->IsOneByteEqualTo(
       "foob"));
   CHECK(declarations->AtForTest(12)->proxy()->var()->mode() == i::CONST);
   CHECK(!declarations->AtForTest(12)->proxy()->var()->binding_needs_init());
   CHECK(declarations->AtForTest(12)->proxy()->var()->location() ==
         i::VariableLocation::MODULE);
 
   i::ModuleDescriptor* descriptor = module_scope->module();
   CHECK_NOT_NULL(descriptor);
 
-  CHECK_EQ(5, descriptor->module_requests().size());
+  CHECK_EQ(5u, descriptor->module_requests().size());
   for (const auto& elem : descriptor->module_requests()) {
     if (elem.first->IsOneByteEqualTo("m.js"))
       CHECK_EQ(elem.second, 0);
     else if (elem.first->IsOneByteEqualTo("n.js"))
       CHECK_EQ(elem.second, 1);
     else if (elem.first->IsOneByteEqualTo("p.js"))
       CHECK_EQ(elem.second, 2);
     else if (elem.first->IsOneByteEqualTo("q.js"))
       CHECK_EQ(elem.second, 3);
     else if (elem.first->IsOneByteEqualTo("bar.js"))
       CHECK_EQ(elem.second, 4);
     else
       CHECK(false);
   }
 
   CHECK_EQ(3, descriptor->special_exports().length());
   CheckEntry(descriptor->special_exports().at(0), "b", nullptr, "a", 0);
   CheckEntry(descriptor->special_exports().at(1), nullptr, nullptr, nullptr, 2);
   CheckEntry(descriptor->special_exports().at(2), "bb", nullptr, "aa",
              0);  // !!!
 
-  CHECK_EQ(8, descriptor->regular_exports().size());
+  CHECK_EQ(8u, descriptor->regular_exports().size());
   entry = descriptor->regular_exports()
               .find(declarations->AtForTest(3)->proxy()->raw_name())
               ->second;
   CheckEntry(entry, "foo", "foo", nullptr, -1);
   entry = descriptor->regular_exports()
               .find(declarations->AtForTest(4)->proxy()->raw_name())
               ->second;
   CheckEntry(entry, "goo", "goo", nullptr, -1);
   entry = descriptor->regular_exports()
               .find(declarations->AtForTest(5)->proxy()->raw_name())
               ->second;
   CheckEntry(entry, "hoo", "hoo", nullptr, -1);
   entry = descriptor->regular_exports()
               .find(declarations->AtForTest(6)->proxy()->raw_name())
               ->second;
   CheckEntry(entry, "joo", "joo", nullptr, -1);
   entry = descriptor->regular_exports()
               .find(declarations->AtForTest(7)->proxy()->raw_name())
               ->second;
   CheckEntry(entry, "default", "*default*", nullptr, -1);
   entry = descriptor->regular_exports()
               .find(declarations->AtForTest(12)->proxy()->raw_name())
               ->second;
   CheckEntry(entry, "foob", "foob", nullptr, -1);
   // TODO(neis): The next lines are terrible. Find a better way.
   auto name_x = declarations->AtForTest(0)->proxy()->raw_name();
-  CHECK_EQ(2, descriptor->regular_exports().count(name_x));
+  CHECK_EQ(2u, descriptor->regular_exports().count(name_x));
   auto it = descriptor->regular_exports().equal_range(name_x).first;
   entry = it->second;
   if (entry->export_name->IsOneByteEqualTo("y")) {
     CheckEntry(entry, "y", "x", nullptr, -1);
     entry = (++it)->second;
     CheckEntry(entry, "x", "x", nullptr, -1);
   } else {
     CheckEntry(entry, "x", "x", nullptr, -1);
     entry = (++it)->second;
     CheckEntry(entry, "y", "x", nullptr, -1);
   }
 
   CHECK_EQ(2, descriptor->namespace_imports().length());
   CheckEntry(descriptor->namespace_imports().at(0), nullptr, "loo", nullptr, 4);
   CheckEntry(descriptor->namespace_imports().at(1), nullptr, "foob", nullptr,
              4);
 
-  CHECK_EQ(4, descriptor->regular_imports().size());
+  CHECK_EQ(4u, descriptor->regular_imports().size());
   entry = descriptor->regular_imports()
               .find(declarations->AtForTest(1)->proxy()->raw_name())
               ->second;
   CheckEntry(entry, nullptr, "z", "q", 0);
   entry = descriptor->regular_imports()
               .find(declarations->AtForTest(2)->proxy()->raw_name())
               ->second;
   CheckEntry(entry, nullptr, "n", "default", 1);
   entry = descriptor->regular_imports()
               .find(declarations->AtForTest(9)->proxy()->raw_name())
@@ skipping 2122 matching lines @@
     const char* data[] = {
       "const arguments = 1",
       "let arguments",
       "var arguments",
       NULL
     };
     // clang-format on
     RunParserSyncTest(context_data, data, kSuccess);
   }
 }