Breaking: #60559 - T3skin Backend Login Javascript File Moved

See Issue #60559

Description

Javascript files of the backend login form moved from EXT:t3skin to EXT:backend.

Impact

Javascript or file not found errors.

Affected installations

An installation is affected if a 3rd party extension includes EXT:t3skin/Resources/Public/JavaScript/login.js

Migration

Include EXT:backend/Resources/Public/JavaScript/login.js instead or refactor the affected extension to free it from the dependency to this core internal file.