Landscape layout has purple margins on the side in Focus, but not Firefox

[cpeterso]

Steps to reproduce

1. Load a web page in Focus, such as https://example.com/
2. Rotate your phone to landscape orientation.

Expected behavior

The page’s landscape layout spills look the same in Focus and Firefox.

Actual behavior

The page’s landscape layout has purple margins on the side in Focus, but not Firefox. I think this is a regression.

Device & build information

• Device: iPhone 12 running iOS 16.2
• Build version: Focus 108.1

┆Issue is synchronized with this Jira Task

[cpeterso]

Focus 108.1 screenshot:

[cpeterso]

Firefox Nightly 9000 (25809) screenshot:

[cpeterso]

Due to this bug, the “swipe from left edge of screen” gesture to navigate back doesn’t work in landscape orientation.