DevTools: aXe core linting for Elements - Properties pane

This adds an automated run of the aXe Core linter to the DOM Properties
pane of the Elements tab.

Change-Id: I3cd687358eea482ec690c8d4bbc53e58ae87fcdb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1567909Reviewed-by: Joel Einbinder <einbinder@chromium.org>
Commit-Queue: Robert Paveza <Rob.Paveza@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#652414}

third_party/blink/web_tests/http/tests/devtools/a11y-axe-core/basic-a11y-test-expected.txt

+Tests accessibility in the elements.domProperties view using the axe-core linter.
+aXe violations: []
+
 Tests accessibility in the performance.monitor view using the axe-core linter.
 aXe violations: []
 

third_party/blink/web_tests/http/tests/devtools/a11y-axe-core/basic-a11y-test.js

@@ -6,6 +6,8 @@
   await TestRunner.loadModule('axe_core_test_runner');
   const locationsToTest =
     [
+      // elements
+      'elements.domProperties',
       // Performance Monitor
       'performance.monitor',
       // Sensors