URL bar does not change position/size when navigating from about:newtab

[bsclifton]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests). N/A
• Ran git rebase -i to squash commits (if needed).

URL bar does not change position/size when navigating from about:newtab to an actual URL.

Fixes #4303

Auditors: @srirambv

Test Plan:

1. Launch Brave (any platform) and open a new blank tab
2. Notice the size/position of the URL bar (both left and right sides)
3. Navigate to http://example.com
4. Notice the size and position of the URL bar do not change

[bbondy]

++