[eslint] Enable rule that prevents exporting UIStrings objects

The CL was automatically generated by the rule itself as it includes
a fix to remove the export keyword.

[email protected], [email protected]

Bug: chromium:1180760
Change-Id: I6571e1274e42a44cd01d98d08adb11b1ae68bf31
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2720369
Commit-Queue: Simon Zünd <[email protected]>
Reviewed-by: Peter Marshall <[email protected]>
Reviewed-by: Jack Franklin <[email protected]>
diff --git a/front_end/.eslintrc.js b/front_end/.eslintrc.js
index 689eba2..0a6f356 100644
--- a/front_end/.eslintrc.js
+++ b/front_end/.eslintrc.js
@@ -7,6 +7,11 @@
 rulesDirPlugin.RULES_DIR = path.join(__dirname, '..', 'scripts', 'eslint_rules', 'lib');
 
 module.exports = {
+  'rules': {
+    // L10n rules are only relevant in 'front_end'.
+    'rulesdir/l10n_filename_matches': 2,
+    'rulesdir/l10n_no_uistrings_export': 2,
+  },
   'overrides': [
     {
       'files': ['*.ts'],