Update V8 DEPS.

DEPS

 # Note: The buildbots evaluate this file with CWD set to the parent
 # directory and assume that the root of the checkout is in ./v8/, so
 # all paths in here must match this assumption.
 
 vars = {
   "git_url": "https://chromium.googlesource.com",
 }
 
 deps = {
   "v8/build":
-    Var("git_url") + "/chromium/src/build.git" + "@" + "0942801bf0d49016e44591d3e47ad3f41ad2d8a4",
+    Var("git_url") + "/chromium/src/build.git" + "@" + "6d146149b533ff2223abf1523d097e21884a2595",
   "v8/tools/gyp":
     Var("git_url") + "/external/gyp.git" + "@" + "e7079f0e0e14108ab0dba58728ff219637458563",
   "v8/third_party/icu":
     Var("git_url") + "/chromium/deps/icu.git" + "@" + "b5ecbb29a26532f72ef482569b223d5a51fd50bf",
   "v8/buildtools":
-    Var("git_url") + "/chromium/buildtools.git" + "@" + "031420bbafaaa8c33e2bc0623c22fb6181a57f47",
+    Var("git_url") + "/chromium/buildtools.git" + "@" + "55638fe5c31652a808f059027b99b08bafd15fb7",
   "v8/base/trace_event/common":
     Var("git_url") + "/chromium/src/base/trace_event/common.git" + "@" + "54b8455be9505c2cb0cf5c26bb86739c236471aa",
   "v8/tools/mb":
-    Var('git_url') + '/chromium/src/tools/mb.git' + '@' + "18b92420fb0cb4378c9496b966507842b99d56b5",
+    Var('git_url') + '/chromium/src/tools/mb.git' + '@' + "1b8214f7fe4354b36d90b62086d844dae0c71747",
   "v8/tools/swarming_client":
     Var('git_url') + '/external/swarming.client.git' + '@' + "7f63a272f7d9785ce41b6d10bb3106c49a968e57",
   "v8/testing/gtest":
     Var("git_url") + "/external/github.com/google/googletest.git" + "@" + "6f8a66431cb592dad629028a50b3dd418a408c87",
   "v8/testing/gmock":
     Var("git_url") + "/external/googlemock.git" + "@" + "0421b6f358139f02e102c9c332ce19a33faf75be",
   "v8/test/benchmarks/data":
     Var("git_url") + "/v8/deps/third_party/benchmarks.git" + "@" + "05d7188267b4560491ff9155c5ee13e207ecd65f",
   "v8/test/mozilla/data":
     Var("git_url") + "/v8/deps/third_party/mozilla-tests.git" + "@" + "f6c578a10ea707b1a8ab0b88943fe5115ce2b9be",
@@ skipping 203 matching lines @@
     'name': 'clang',
     'pattern': '.',
     'action': ['python', 'v8/tools/clang/scripts/update.py', '--if-needed'],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
     "action": ["python", "v8/gypfiles/gyp_v8"],
   },
 ]