Task/Issue URL: https://app.asana.com/1/137249556945/project/715106103902962/task/1210318103652397

Description

This PR fixes an issue when the bottom omnibar jump when the keyboard is shown/hidden.

Steps to test this PR

Omnibar animation

• Set the omnibar to the bottom position in the Appearance settings
• Go to the browser and select the address bar to show the keyboard
• Verify the omnibar moves along the keyboard as it moves up
• Tap on the back arrow in the omnibar to remove the focus
• Verify the omnibar moves along the keyboard as it moves down

Omnibar hiding

• Open a website with an element fixed at the bottom (i.e. theguardian.com)
• Notice the bottom-anchored element is fully visible
• Swipe the website up to hide the omnibar
• Notice that as the omnibar hides, the web content expands
• Swipe the website down to expand the omnibar
• Notice the web content moves up and is fully visible

UI changes