Do not export libdart symbols (flutter#6337)

goderbauer · web-flow · commit 763627fff5bb · 2018-09-27T18:19:22.000+02:00
diff --git a/tools/gn b/tools/gn
@@ -113,6 +113,8 @@ def to_gn_args(args):
     else:
       aot = False
 
+    gn_args['dart_lib_export_symbols'] = False
+
     if runtime_mode == 'debug':
         gn_args['dart_runtime_mode'] = 'develop'
     elif runtime_mode == 'dynamic_profile':
