Add myself as an OWNER for third_party/blink/public/

Change-Id: Ic6b3b590cc3efde171ebc5c4686c384d406310d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2013515Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733855}

third_party/blink/public/OWNERS

 chrishtr@chromium.org
 dcheng@chromium.org
 dgozman@chromium.org
+dtapuska@chromium.org
 falken@chromium.org
 foolip@chromium.org
 haraken@chromium.org