[ESlint] Enable CSS Check Import rule

Follow-up enabling the CSS Check Import rule introduced in https://crrev.com/c/2953260

[email protected]

Bug: 1106746
Change-Id: Id19487d2b6a1d1ed966e01c35d39485f05d301b6
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3276919
Auto-Submit: John Emau <[email protected]>
Commit-Queue: Jack Franklin <[email protected]>
Reviewed-by: Jack Franklin <[email protected]>
diff --git a/front_end/.eslintrc.js b/front_end/.eslintrc.js
index b2b71a6..8ba503c 100644
--- a/front_end/.eslintrc.js
+++ b/front_end/.eslintrc.js
@@ -32,6 +32,7 @@
         'rulesdir/ban_style_tags_in_lit_html': 2,
         'rulesdir/ban_a_tags_in_lit_html': 2,
         'rulesdir/check_component_naming': 2,
+        'rulesdir/check_css_import': 2,
         'rulesdir/check_was_shown_methods': 2,
         'rulesdir/static_custom_event_names': 2,
         'rulesdir/lit_html_host_this': 2,