Fix mobile navigation in macOS Safari

[colebemis]

Problem

In macOS Safari, clicking links below the fold in the responsive navigation drawer causes focus to jump to the first link instead of going the destination of the link.

Here's a codesandbox that reproduces the issue: https://codesandbox.io/s/responsive-navigation-safari-bug-6hvj4

Notes

• Removing the FocusLock component from the Drawer component fixes this issue.

• Removing tabIndex="-1" from the wrapper div created by @reach/router also fixes this issue:

  

[colebemis]

Closed by #66