GN: Build app snapshots for the SDK tools.

tools/gn.py

Index: tools/gn.py
diff --git a/tools/gn.py b/tools/gn.py
index 2f8d664301bc84b8041e1d57dc7066fe4d589f64..4afbe9df97bd93a991e2b3272b4ae3e923f500db 100755
--- a/tools/gn.py
+++ b/tools/gn.py
@@ -120,6 +120,12 @@ def to_gn_args(args, mode, arch, target_os):
   if args.toolchain_prefix:
     gn_args['toolchain_prefix'] = args.toolchain_prefix
 
+  # If we are on ia32 or cross-compiling, use app snapshots without code for the SDK.
+  if arch == 'ia32' or gn_args['target_cpu'] != gn_args['host_cpu']:
+    gn_args['dart_app_snapshot_kind'] = 'app-after-run'
+  else:
+    gn_args['dart_app_snapshot_kind'] = 'app-jit-after-run'
+
   goma_dir = os.environ.get('GOMA_DIR')
   goma_home_dir = os.path.join(os.getenv('HOME', ''), 'goma')
   if args.goma and goma_dir: