Roll src/third_party/devtools-frontend/src bf2de16258dc..8ef250cfe144 (3 commits)

https://chromium.googlesource.com/devtools/devtools-frontend.git/+log/bf2de16258dc..8ef250cfe144

git log bf2de16258dc..8ef250cfe144 --date=short --first-parent --format='%ad %ae %s'
2020-02-20 tvanderlippe@chromium.org Remove typedefs from {perf_ui,persistence,protocol}-legacy.js
2020-02-20 tvanderlippe@chromium.org Add e2etest for cacheable responses in the network panel
2020-02-20 tvanderlippe@chromium.org Add test for utf-8 character encoding

Created with:
  gclient setdep -r src/third_party/devtools-frontend/src@8ef250cfe144

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/devtools-frontend-chromium
Please CC devtools-waterfall-sheriff-onduty@grotations.appspotmail.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

Bug: chromium:1006759,chromium:1044632
Tbr: devtools-waterfall-sheriff-onduty@grotations.appspotmail.com
Change-Id: Ie96e85bdabc6c432b4ab251cc069912b827a782a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2066089Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#743198}

DEPS

@@ -242,7 +242,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling devtools-frontend
   # and whatever else without interference from each other.
-  'devtools_frontend_revision': 'bf2de16258dc7edce1da48f05523c349ab567976',
+  'devtools_frontend_revision': '8ef250cfe14410a3afef90ffd28731b218391a55',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling libprotobuf-mutator
   # and whatever else without interference from each other.