Update V8 to version 4.7.39.

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 21 matching lines @@
   # If you do not know, use the full path while defining your new deps entry.
   'googlecode_url': 'http://%s.googlecode.com/svn',
   'webkit_revision': '9e499997d36e8976463dceea20e5ffb4378c36b1', # from svn revision 201944
   'chromium_git': 'https://chromium.googlesource.com',
   'libvpx_revision': '0304cef02fe5e94b63e7e78ddb263d91ca32d533',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
   'skia_revision': '036fd8e6f66b53cf87a5f91083cae82f0aeb3635',
   # 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': 'ab6f1f019a6db0ff7ab9541208a57a33d115ef8e',
+  'v8_revision': '242115babdfda184745019ba04f5844a8f4a5085',
   # 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': '49f046853671bbd5ab65509a8049d36ac0224714',
   # 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': 'a0a9e12ded57c70f28a3f467fafe100e32a684e5',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
@@ skipping 751 matching lines @@
     'pattern': '.',
     'action': [
         'python',
         'src/tools/check_git_config.py',
         '--running-as-hook',
     ],
   },
 ]