Update V8 DEPS.

Rolling v8/third_party/icu to c81a1a3989c3b66fa323e9a6ee7418d7c08297af

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/1213043007

Cr-Commit-Position: refs/heads/master@{#29505}

DEPS

@@ -10,7 +10,7 @@ deps = {
   "v8/build/gyp":
     Var("git_url") + "/external/gyp.git" + "@" + "5122240c5e5c4d8da12c543d82b03d6089eb77c5",
   "v8/third_party/icu":
-    Var("git_url") + "/chromium/deps/icu.git" + "@" + "7fe225d77f307fdbe24695179a84336ef95c1253",
+    Var("git_url") + "/chromium/deps/icu.git" + "@" + "c81a1a3989c3b66fa323e9a6ee7418d7c08297af",
   "v8/buildtools":
     Var("git_url") + "/chromium/buildtools.git" + "@" + "ecc8e253abac3b6186a97573871a084f4c0ca3ae",
   "v8/testing/gtest":