No fix: Improve the quality of engine script injection on sub frames

[cuba]

Summary of Changes

This pull request fixes #

Submitter Checklist:

• [ ] Unit Tests are updated to cover new or changed functionality
• [ ] User-facing strings use NSLocalizableString()
• [ ] New or updated UI has been tested across:
  • [ ] Light & dark mode
  • [ ] Different size classes (iPhone, landscape, iPad)
  • [ ] Different dynamic type sizes

Test Plan:

Screenshots:

Reviewer Checklist:

• [ ] Issues include necessary QA labels:
  • QA/(Yes|No)
  • bug / enhancement
• [ ] Necessary security reviews have taken place.
• [ ] Adequate unit test coverage exists to prevent regressions.
• [ ] Adequate test plan exists for QA to validate (if applicable).
• [ ] Issue and pull request is assigned to a milestone (should happen at merge time).