Fix #3763: Update initial height of menu when page actions are visible

[kylehickinson]

Summary of Changes

This pull request fixes #3763

Submitter Checklist:

• Unit Tests are updated to cover new or changed functionality
• User-facing strings use NSLocalizableString()

Test Plan:

On iPhone only

• Open menu on NTP, height should be the same as previous versions
• Visit a web page
• Open menu, verify it is taller and you can access "Share to…" without scrolling

Reviewer Checklist:

• Issues include necessary QA labels:
  • QA/(Yes|No)
  • release-notes/(include|exclude)
  • 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 is assigned to a milestone (should happen at merge time).