[Devtools] Move accessibilityInspection to defaultExperiments

Bug: 390254
Change-Id: I3fc5b0ac80fe861c04b0bbe72ec93438bbf25145
Reviewed-on: https://chromium-review.googlesource.com/698844
Commit-Queue: Alice Boxhall <aboxhall@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509691}

third_party/WebKit/Source/devtools/front_end/main/Main.js

@@ -159,7 +159,7 @@ Main.Main = class {
 
     Runtime.experiments.setDefaultExperiments([
       'continueToLocationMarkers', 'autoAttachToCrossProcessSubframes', 'objectPreviews', 'persistence2',
-      'networkGroupingRequests', 'timelineColorByProduct'
+      'networkGroupingRequests', 'timelineColorByProduct', 'accessibilityInspection'
     ]);
   }