Update V8 DEPS.

Rolling v8/build to 38a9cfaa10bf2b91c52f8a9ef4449723dd7aa706

Rolling v8/tools/mb to 99788b8b516c44d7db25cfb68695bc234fdee5ed

TBR=machenbach@chromium.org,vogelheim@chromium.org,hablich@chromium.org

Review-Url: https://codereview.chromium.org/2267513002
Cr-Commit-Position: refs/heads/master@{#38765}

DEPS

@@ -8,7 +8,7 @@ vars = {
 
 deps = {
   "v8/build":
-    Var("git_url") + "/chromium/src/build.git" + "@" + "d158ac9f154829bb0a57c2fd398972482cebef28",
+    Var("git_url") + "/chromium/src/build.git" + "@" + "38a9cfaa10bf2b91c52f8a9ef4449723dd7aa706",
   "v8/tools/gyp":
     Var("git_url") + "/external/gyp.git" + "@" + "702ac58e477214c635d9b541932e75a95d349352",
   "v8/third_party/icu":
@@ -26,7 +26,7 @@ deps = {
   "v8/third_party/markupsafe":
     Var("git_url") + "/chromium/src/third_party/markupsafe.git" + "@" + "484a5661041cac13bfc688a26ec5434b05d18961",
   "v8/tools/mb":
-    Var('git_url') + '/chromium/src/tools/mb.git' + '@' + "f3036b2e34d746db3635afa0841f51019b2b8d38",
+    Var('git_url') + '/chromium/src/tools/mb.git' + '@' + "99788b8b516c44d7db25cfb68695bc234fdee5ed",
   "v8/tools/swarming_client":
     Var('git_url') + '/external/swarming.client.git' + '@' + "e4288c3040a32f2e7ad92f957668f2ee3d36e5a6",
   "v8/testing/gtest":