Update DevTools DEPS (trusted)

Rolling buildtools: https://chromium.googlesource.com/chromium/src/buildtools/+log/6f35929..299cb62

Roll created at https://cr-buildbucket.appspot.com/build/8718792226657037041

Bug: none
Change-Id: Ifced120fd0fd726ab6c0168131966197328e092c
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6421378
Commit-Queue: Devtools Autoroller <devtools-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Devtools Autoroller <devtools-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>

Author: devtools-ci-autoroll-builder

DEPS

@@ -15,7 +15,7 @@ vars = {
   'build_revision': 'e13953ced04ed05f45aa3c961bd6d802aced74ec',
 
   'buildtools_url': 'https://chromium.googlesource.com/chromium/src/buildtools.git',
-  'buildtools_revision': '6f359296daa889aa726f3d05046b9f37be241169',
+  'buildtools_revision': '299cb62c60f608d3b152fd3ba337f4e084e1a3b4',
 
   'depot_tools_url': 'https://chromium.googlesource.com/chromium/tools/depot_tools.git',
   'depot_tools_revision': 'f40ddcd8d51626fb7be3ab3c418b3f3be801623f',