Fix four dangling header-file references in .gyp files

cc/cc.gyp

 # Copyright (c) 2012 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 528 matching lines @@
         'trees/occlusion.cc',
         'trees/occlusion.h',
         'trees/occlusion_tracker.cc',
         'trees/occlusion_tracker.h',
         'trees/property_tree.cc',
         'trees/property_tree.h',
         'trees/property_tree_builder.cc',
         'trees/property_tree_builder.h',
         'trees/proxy.cc',
         'trees/proxy.h',
-        'trees/proxy_impl.h'
-        'trees/proxy_main.h'
+        'trees/proxy_impl.h',
+        'trees/proxy_main.h',
         'trees/scoped_abort_remaining_swap_promises.h',
         'trees/single_thread_proxy.cc',
         'trees/single_thread_proxy.h',
         'trees/swap_promise_monitor.cc',
         'trees/swap_promise_monitor.h',
         'trees/threaded_channel.cc',
         'trees/threaded_channel.h',
         'trees/thread_proxy.cc',
         'trees/thread_proxy.h',
         'trees/tree_synchronizer.cc',
@@ skipping 56 matching lines @@
         'surfaces/surface_resource_holder.cc',
         'surfaces/surface_resource_holder.h',
         'surfaces/surfaces_export.h',
       ],
       'includes': [
         '../build/android/increase_size_for_speed.gypi',
       ],
     },
   ],
 }