[gn] Restore strict-aliasing for gn on mac

BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/dcheck_always_on.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
@@ skipping 273 matching lines @@
   if (v8_target_cpu == "x64") {
     defines += [ "V8_TARGET_ARCH_X64" ]
     if (is_win) {
       # Increase the initial stack size. The default is 1MB, this is 2MB. This
       # applies only to executables and shared libraries produced by V8 since
       # ldflags are not pushed to dependants.
       ldflags += [ "/STACK:2097152" ]
     }
   }
 
+  if (is_mac) {
+    cflags += [ "-fstrict-aliasing" ]
+  }
+
   # TODO(jochen): Support v8_enable_prof on Windows.
   # TODO(jochen): Add support for compiling with simulators.
 
   if (is_debug) {
     if (is_linux && v8_enable_backtrace) {
       ldflags += [ "-rdynamic" ]
     }
 
     # TODO(jochen): Add support for different debug optimization levels.
     defines += [
@@ skipping 2095 matching lines @@
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [ ":internal_config" ]
 }
 
 v8_fuzzer("wasm_asmjs_fuzzer") {
 }