Update DevTools DEPS (trusted)

Rolling buildtools: https://chromium.googlesource.com/chromium/src/buildtools/+log/bf449a9..b905071

Roll created at https://cr-buildbucket.appspot.com/build/8709041729556235617

Bug: none
Change-Id: I37d66d95db98ec614e459b193352dd21b530a7e3
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6768580
Bot-Commit: Devtools Autoroller <devtools-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: 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': 'bf449a9e19dce934d300ceef76c19326ff00a940',
+  'buildtools_revision': 'b9050718cd8ee119996c515e8abe9ba65a4f4367',
 
   'depot_tools_url': 'https://chromium.googlesource.com/chromium/tools/depot_tools.git',
   'depot_tools_revision': '5e6b39291412822ad5f14c1dccf9a4c6d062ad1f',