Fix typo in experimental/webtry/DESIGN.md.
Fix typo in experimental/webtry/DESIGN.md.

R=tfarina@chromium.org

Author: jcgregorio@google.com

Review URL: https://codereview.chromium.org/593723003

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