Remove obsolete make_file_array() uses from web/BUILD.gn

This is a simple follow-up to
  https://codereview.chromium.org/364323002/
removing from web/BUILD.gn what that CL removed from web.gyp.

BUG=312586

Review URL: https://codereview.chromium.org/372983004

git-svn-id: svn://svn.chromium.org/blink/trunk@177687 bbb929c8-8fbe-4397-9dbb-9b2b20218538