Update V8 to version 4.7.74.1 (cherry-pick).

DEPS

 # This file is used to manage the dependencies of the Chromium src repo. It is
 # used by gclient to determine what version of each dependency to check out, and
 # where.
 #
 # For more information, please refer to the official documentation:
 #   https://sites.google.com/a/chromium.org/dev/developers/how-tos/get-the-code
 #
 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 #
@@ skipping 20 matching lines @@
   # Use this googlecode_url variable only if there is an internal mirror for it.
   # If you do not know, use the full path while defining your new deps entry.
   'googlecode_url': 'http://%s.googlecode.com/svn',
   'chromium_git': 'https://chromium.googlesource.com',
   'libvpx_revision': '70db2235b7e389f4d1b178320ebce76280c127af',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
   'skia_revision': '17e3806837774b79f37a8dda018b6c4a08f9c444',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.
-  'v8_revision': '76d0303374b12252aac0574027be114a397cf35c',
+  'v8_revision': '40d687146a2c35b1328f21ea5f3b95b2be4dda52',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.
   'swarming_revision': '6e5d2b21f0ac98396cd736097a985346feed1328',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
   'angle_revision': '69cce580d31bff286d9b44349919e9a1f7386ea0',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
@@ skipping 752 matching lines @@
     'name': 'check_git_config',
     'pattern': '.',
     'action': [
         'python',
         'src/tools/check_git_config.py',
         '--running-as-hook',
     ],
   },
 ]