Add tex files to gr-syntax-layer's language map. Also update hljs to d24895f4 to include this fix: [1] fix(parser) Make language alias registration case insensitive [1] https://github.com/highlightjs/highlight.js/pull/3026 Bug: Issue 14091 Change-Id: I41f855703f0a9d70b6aebd2a337f1c4c7bf91904