Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/3d9873f..29568c1

Rolling v8/third_party/depot_tools: https://chromium.googlesource.com/chromium/tools/depot_tools/+log/0daedf7..b250ec1

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

Change-Id: Ifbe08a9e1f1dc077c7e5e253c483dfab6a648ebe
Reviewed-on: https://chromium-review.googlesource.com/c/1260255Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#56362}

DEPS

@@ -13,9 +13,9 @@ vars = {
 
 deps = {
   'v8/build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '3d9873fa44b21b7c2fb624f016ad4eb197b9fab1',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '29568c1af459b70973d58077d33e0ac196da22a6',
   'v8/third_party/depot_tools':
-    Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + '0daedf7758e157ee22a64e9dabcb089c0da5ef4c',
+    Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + 'b250ec16d39169c4f7df3f9ae40230934d0f4ddb',
   'v8/third_party/icu':
     Var('chromium_url') + '/chromium/deps/icu.git' + '@' + 'c52a2a250d6c5f5cbdd015dff36af7c5d0ae1150',
   'v8/third_party/instrumented_libraries':