Don't let the details display get out of control.
Don't let the details display get out of control.

Limit the number of tests that get expanded and pop up toast with a warning.

Screenshot:

  https://screenshot.googleplex.com/dY8NK9FAvgc.png

BUG=skia:

Review URL: https://codereview.chromium.org/1135093002

Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot