Infrastructure for reading V8's initial snapshot from external files

mojo/mojo_js_unittests.isolate

 # Copyright 2014 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.
 {
   'includes': [
     '../third_party/icu/icu.isolate',
+    '../gin/v8.isolate',
   ],
   'conditions': [
     ['OS=="win" or OS=="mac" or OS=="linux"', {
       'variables': {
         'command': [
           '../testing/test_env.py',
           '<(PRODUCT_DIR)/mojo_js_unittests<(EXECUTABLE_SUFFIX)',
           '--brave-new-test-launcher',
           '--test-launcher-bot-mode',
         ],
@@ skipping 23 matching lines @@
     }],
     ['OS=="mac"', {
       'variables': {
         'files': [
           '<(PRODUCT_DIR)/libmojo_test_support.dylib',
         ],
       },
     }],
   ],
 }