Add core/dom/{events,ng}/OWNERS files

Add me as an owner of these directories.

Change-Id: I0baadafda1c4989956dd477b6e6ddab0195916ea
Reviewed-on: https://chromium-review.googlesource.com/923746Reviewed-by: Takayoshi Kochi <kochi@chromium.org>
Commit-Queue: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537596}

third_party/WebKit/Source/core/dom/events/OWNERS

+hayato@chromium.org
+
+# TEAM: dom-dev@chromium.org
+# COMPONENT: Blink>DOM

third_party/WebKit/Source/core/dom/ng/OWNERS

+hayato@chromium.org
+
+# TEAM: dom-dev@chromium.org
+# COMPONENT: Blink>DOM