fix(parser) Make language alias registration case insensitive (#3026)

Author: davido

CHANGES.md

@@ -29,6 +29,7 @@ Deprecations:
 API:
 
 - enh(api) add `unregisterLanguage` method (#3009) [Antoine du Hamel][]
+- enh: Make alias registration case insensitive (#3026) [David Ostrovsky][]
 
 [Stef Levesque]: https://github.com/stef-levesque
 [Josh Goebel]: https://github.com/joshgoebel
@@ -38,6 +39,7 @@ API:
 [Vyron Vasileiadis]: https://github.com/fedonman
 [Antoine du Hamel]: https://github.com/aduh95
 [Vaibhav Chanana]: https://github.com/il3ven
+[David Ostrovsky]: https://github.com/davido
 
 ## Version 10.6.0
 

src/highlight.js

@@ -875,7 +875,7 @@ const HLJS = function(hljs) {
     if (typeof aliasList === 'string') {
       aliasList = [aliasList];
     }
-    aliasList.forEach(alias => { aliases[alias] = languageName; });
+    aliasList.forEach(alias => { aliases[alias.toLowerCase()] = languageName; });
   }
 
   /**