Update V8 to version 4.6.67.

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': '4d062fadd2aa51b0c6840cd7e53a79a743094b01', # from svn revision 200356
   'chromium_git': 'https://chromium.googlesource.com',
   'libvpx_revision': '19bcff869995b401194074278634e6b5cf391333',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
   'skia_revision': '2ccdb636e8618db77be8e05cdacd82c249c6898c',
   # 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': 'e348bba636df70eeb20ea73872d899300b8bbe63',
+  'v8_revision': '686ae5061f3111ec82bb37a987ad81ef866a9042',
   # 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': '2866a22530cb65feae5d9f64c83636aed5391d06',
   # 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': 'b4b0b48247f285c7326c7729c49c04b3cc1aa319',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
@@ skipping 748 matching lines @@
     'pattern': '.',
     'action': [
         'python',
         'src/tools/check_git_config.py',
         '--running-as-hook',
     ],
   },
 ]