Correct error in unused locale string

locale/en-US.properties

@@ -9,7 +9,7 @@ safest_label = Safest
 safest_description = Only allows website features required for static and basic services. These changes affect images, media, and scripts.
 safest_list_label = At the safest setting
 learn_more_label = Learn More
-js_on_https_sites_only = JavaScript is disabled on non-HTTP sites.
+js_on_https_sites_only = JavaScript is disabled on non-HTTPS sites.
 js_disabled = JavaScript is disabled by default on all sites.
 limit_typography = Some fonts and math symbols are disabled.
 limit_graphics_and_typography = Some fonts, icons, math symbols and images are disabled.