Teach i18nTemplate.process() to handle <link rel=import> and <template>

ui/webui/resources/js/compiled_resources2.gyp

 # Copyright 2015 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.
 {
   'targets': [
     {
       'target_name': 'action_link',
       'includes': ['../../../../third_party/closure_compiler/compile_js2.gypi'],
     },
     {
@@ skipping 24 matching lines @@
         'cr',
       ],
       'includes': ['../../../../third_party/closure_compiler/compile_js2.gypi'],
     },
     {
       'target_name': 'parse_html_subset',
       'includes': ['../../../../third_party/closure_compiler/compile_js2.gypi'],
     },
     {
       'target_name': 'i18n_template_no_process',
-      'dependencies': ['load_time_data'],
+      'dependencies': [
+        'load_time_data',
+        '<(EXTERNS_GYP):pending_compiler_externs',
+      ],
       'includes': ['../../../../third_party/closure_compiler/compile_js2.gypi'],
     },
     {
       'target_name': 'i18n_template',
-      'dependencies': ['load_time_data'],
+      'dependencies': [
+        'load_time_data',
+        # Ideally, <include> would automatically import externs as well, but
+        # it current doesn't and that sounds hard. Let's just kill <include>.
+        '<(EXTERNS_GYP):pending_compiler_externs',
+      ],
       'includes': ['../../../../third_party/closure_compiler/compile_js2.gypi'],
     },
   ],
 }