Roll src/third_party/devtools-frontend/src f996a1c537a0..b6cad595a9df (3 commits)

https://chromium.googlesource.com/devtools/devtools-frontend.git/+log/f996a1c537a0..b6cad595a9df

git log f996a1c537a0..b6cad595a9df --date=short --first-parent --format='%ad %ae %s'
2020-03-03 szuend@chromium.org Prepare SASSSourceMapping.js for asynchronous live locations
2020-03-03 szuend@chromium.org [utilities] Use Set instead of Array for TargetModel._observers
2020-03-03 szuend@chromium.org [utilities] Use Set instead of Array for tree outlines in SourcesPanel

Created with:
  gclient setdep -r src/third_party/devtools-frontend/src@b6cad595a9df

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:1032016,chromium:1050549
Tbr: devtools-waterfall-sheriff-onduty@grotations.appspotmail.com
Change-Id: I61b1040459a16036bef6edd9827470cebf3b36e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2084438Reviewed-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@{#746303}

DEPS

@@ -246,7 +246,7 @@ 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': 'f996a1c537a0722a2601afe8cb5f81f913a02cb0',
+  'devtools_frontend_revision': 'b6cad595a9dfb67e9703efc9670ed377a79da152',
   # 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.