[gn] Enable stricter build flags

src/wasm/wasm-objects.h

 // Copyright 2016 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_OBJECTS_H_
 #define V8_WASM_OBJECTS_H_
 
 #include "src/debug/debug.h"
 #include "src/debug/interface-types.h"
 #include "src/objects.h"
@@ skipping 276 matching lines @@
   MACRO(SMALL_NUMBER, uint32_t, max_mem_pages)          \
   MACRO(WEAK_LINK, WasmCompiledModule, next_instance)   \
   MACRO(WEAK_LINK, WasmCompiledModule, prev_instance)   \
   MACRO(WEAK_LINK, JSObject, owning_instance)           \
   MACRO(WEAK_LINK, WasmModuleObject, wasm_module)
 
 #if DEBUG
 #define DEBUG_ONLY_TABLE(MACRO) MACRO(SMALL_NUMBER, uint32_t, instance_id)
 #else
 #define DEBUG_ONLY_TABLE(IGNORE)
-  uint32_t instance_id() const { return -1; }
+  uint32_t instance_id() const { return static_cast<uint32_t>(-1); }
 #endif
 
 #define WCM_PROPERTY_TABLE(MACRO) \
   CORE_WCM_PROPERTY_TABLE(MACRO)  \
   DEBUG_ONLY_TABLE(MACRO)
 
  private:
   enum PropertyIndices {
 #define INDICES(IGNORE1, IGNORE2, NAME) kID_##NAME,
     WCM_PROPERTY_TABLE(INDICES) Count
@@ skipping 219 matching lines @@
   };
 };
 
 #undef DECLARE_ACCESSORS
 #undef DECLARE_OPTIONAL_ACCESSORS
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_OBJECTS_H_