Back and Forward Navigation button animation on macOS

[LaurenWags]

Description

On browser-laptop the backward and forward navigation buttons increase in size when swiping on the macOS trackpad to navigate. Currently this is not implemented in brave-core - unsure if we want to carry this forward. @bradleyrichter @rossmoody thoughts?

Steps to Reproduce

1. Open Brave, navigate to a web page.
2. Use that same tab to navigate either within the site or to different sites, just to generate some tab history.
3. Use the trackpad to navigate by swiping backward and forward

Actual result:

Back/forward buttons to not increase in size, but we do have the same animation on the tab page as chrome to indicate which way you are navigating:

Expected result:

In browser-laptop the buttons get larger to indicate which way you are navigating:

Reproduces how often:

easily

Brave version (about:brave info)

0.54.2 Chromium: 69.0.3497.42

Reproducible on current release:

no

Website problems only:

• Does the issue resolve itself when disabling Brave Shields?
• Is the issue reproducible on the latest version of Chrome?

Additional Information

Unsure if this is needed as b-c has the same on screen animation as chrome now.