webkit_lint failing on chromium.mac/Mac10.9 Tests

Builders failed on: 
- Mac10.9 Tests: 
  https://build.chromium.org/p/chromium.mac/builders/Mac10.9%20Tests


https://chromium-review.googlesource.com/c/chromium/src/+/707507
seems removing support for Mac OS X 10.9 and causing error at webkit_lint.