Re-enable DevTools locations pane test

The test was temporarily disabled (+ its expectations updated) here:
https://chromium-review.googlesource.com/c/chromium/src/+/2119533

DevTools front-end CL that changed the expectations:
https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2119672

The downstream DevTools change rolled into Chromium here:
https://chromium-review.googlesource.com/c/chromium/src/+/2119928

Bug: chromium:1051186, chromium:1051822, chromium:1057096
Change-Id: I1dfa629d3c763171d577ac04e554a6dad652efa1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2119513
Auto-Submit: Mathias Bynens <mathias@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753196}

third_party/blink/web_tests/TestExpectations

@@ -6584,7 +6584,6 @@ crbug.com/1006759 http/tests/devtools/profiler/agents-disabled-check.js [ Skip ]
 
 # DevTools roll
 crbug.com/1052111 http/tests/devtools/a11y-axe-core/audits-start-view-a11y-test.js [ Skip ]
-crbug.com/1051822 http/tests/devtools/a11y-axe-core/settings/locations-a11y-test.js [ Pass Failure ]
 
 # Sheriff 2020-02-18
 crbug.com/1050893 [ Fuchsia ] virtual/gpu/fast/canvas/feimage-with-foreignobject-taint-canvas-2.html [ Timeout Pass ]