Add masonfreed@ to core/OWNERS

Change-Id: I1ad5ef4661d1932eb11f4626ef8cc6277700569e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2031563Reviewed-by: Philip Rogers <pdr@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737135}

third_party/blink/renderer/core/OWNERS

@@ -44,6 +44,7 @@ kenneth.r.christiansen@intel.com
 kinuko@chromium.org
 kojii@chromium.org
 kouhei@chromium.org
+masonfreed@chromium.org
 mkwst@chromium.org
 mstensho@chromium.org
 # nainar reviews changes in core/css,core/style