Fix building codemirror

Change-Id: Id5cc461c412e104a0dea732a406739a0de07a7a5
diff --git a/web/BUILD b/web/BUILD
index 3c91428..f336237 100644
--- a/web/BUILD
+++ b/web/BUILD
@@ -71,6 +71,7 @@
         "@plugins_npm//@codemirror/lang-xml",
         "@plugins_npm//@codemirror/language",
         "@plugins_npm//@codemirror/language-data",
+        "@plugins_npm//@codemirror/legacy-modes",
         "@plugins_npm//@codemirror/lint",
         "@plugins_npm//@codemirror/search",
         "@plugins_npm//@codemirror/state",