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/gyp":
     Var("git_url") + "/external/gyp.git" + "@" + "2889664b9fa88cce175c5c7cdf207d28420a7412",
   "v8/third_party/icu":
-    Var("git_url") + "/chromium/deps/icu.git" + "@" + "46be516de5c83aa0b7b3b75be669b48e7a803290",
+    Var("git_url") + "/chromium/deps/icu.git" + "@" + "e4c31439828d356525b71ef81a6d61ea50d7d673",
   "v8/buildtools":
     Var("git_url") + "/chromium/buildtools.git" + "@" + "3b302fef93f7cc58d9b8168466905237484b2772",
   "v8/testing/gtest":
     Var("git_url") + "/external/googletest.git" + "@" + "be1868139ffe0ccd0e8e3b37292b84c821d9c8ad",
   "v8/testing/gmock":
     Var("git_url") + "/external/googlemock.git" + "@" + "29763965ab52f24565299976b936d1265cb6a271",  # from svn revision 501
   "v8/tools/clang":
     Var("git_url") + "/chromium/src/tools/clang.git" + "@" + "6aa9a498bf4c1567efe9b78da82678ed1e8e3298",
 }
 
@@ skipping 84 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/build/gyp_v8"],
   },
 ]