Use LF line endings for DIR_METADATA

Change-Id: Ie6ee8bfd51acc8317a0ba243d5924f5f87d39359
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2489501Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Henrique Ferreiro <hferreiro@igalia.com>
Cr-Commit-Position: refs/heads/master@{#819451}

.gitattributes

@@ -50,6 +50,7 @@ README   text eol=lf
 README.*   text eol=lf
 WATCHLISTS   text eol=lf
 VERSION   text eol=lf
+DIR_METADATA   text eol=lf
 
 # Skip Tricium by default on files in third_party.
 third_party/** -tricium