Address code review comments.

Author: a-siva

tools/gn

@@ -381,8 +381,7 @@ def to_gn_args(args):
     gn_args['bssl_use_clang_integrated_as'] = True
 
     # Enable pointer compression on 64-bit mobile targets.
-    if (args.target_os == 'android' or args.target_os == 'ios') and (
-        gn_args['target_cpu'] == 'x64' or gn_args['target_cpu'] == 'arm64'):
+    if args.target_os in ['android', 'ios'] and gn_args['target_cpu'] in ['x64' , 'arm64']:
       gn_args['dart_use_compressed_pointers'] = True
 
     return gn_args