WebUI styleguide: Update guidance about on-click vs on-tap handlers.

Bug: 812035
Change-Id: I319cf6149c4bfaac2751687c433a5546be86d116
Reviewed-on: https://chromium-review.googlesource.com/c/1469072
Auto-Submit: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631849}
1 file changed