[gn] Enable stricter build flags

test/unittests/wasm/wasm-macro-gen-unittest.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 "test/unittests/test-utils.h"
 
 #include "src/wasm/wasm-macro-gen.h"
 
 namespace v8 {
 namespace internal {
 namespace wasm {
 
 class WasmMacroGenTest : public TestWithZone {};
 
 #define EXPECT_SIZE(size, ...)                          \
   do {                                                  \
     byte code[] = {__VA_ARGS__};                        \
+    USE(code);                                          \
     EXPECT_EQ(static_cast<size_t>(size), sizeof(code)); \
   } while (false)
 
 TEST_F(WasmMacroGenTest, Constants) {
   EXPECT_SIZE(2, WASM_ONE);
   EXPECT_SIZE(2, WASM_ZERO);
 
   EXPECT_SIZE(2, WASM_I32V_1(-22));
   EXPECT_SIZE(2, WASM_I32V_1(54));
 
@@ skipping 276 matching lines @@
     EXPECT_SIZE(5, WASM_LOAD_MEM_OFFSET(kMemTypes[i], 11, WASM_ZERO));
   }
   for (size_t i = 0; i < arraysize(kMemTypes); i++) {
     EXPECT_SIZE(7, WASM_STORE_MEM_OFFSET(kMemTypes[i], 13, WASM_ZERO,
                                          WASM_GET_LOCAL(0)));
   }
 }
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8