Remove toolbarbutton.type (blank defaults to default button.)
"menu-button" is used for the new bookmark menu and needs another button beside it to complete the borders.

See
https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XUL/Attribute/toolbarbutton.type

Fixes
https://github.com/RequestPolicyContinued/requestpolicy/issues/462
remove toolbarbutton-dropmarker's "display:none" style

this style isn't needed anymore because of commit 02ec2ca