The two scroll arrow icon of bookmarks menu widget dropdown seems to have inverted icons

Reproducible: always

Steps to reproduce:

1. Customize and put Bookmarks menu widget
2. Enable Dark theme from about:addons
3. Bookmark a lot
4. Open the bookmarks menu widget, Observe behavior

Actual results:

• the two icons are inverted

Expected results:

• the two buttons are displayed correctly

Backed out changeset cdc5571c2d7c (Bug 1623015) for causing mochitest failures CLOSED TREE

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&selectedJob=294520690&resultStatus=pending%2Crunning%2Csuccess%2Ctestfailed%2Cbusted%2Cexception&searchStr=ec3fcdb6faf4ef5440aea2542d16416ba2ab7c63&revision=cdc5571c2d7ceaf85f057f57862dc10711aaece4

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=294520690&repo=autoland&lineNumber=2889
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=294518663&repo=autoland&lineNumber=16325

Backout: https://hg.mozilla.org/integration/autoland/rev/87f1271cf700a606444f54f15902918479baaab6

Alexander or Jamie, do you have any clue why this patch fails accessible/tests/mochitest/hittest/test_menu.xhtml and accessible/tests/mochitest/states/test_visibility.xhtml? I'm having a hard time even understanding the failure messages such as wrong state bits for 'mi_file1.2.1' !got '0', expected 'invisible' or state bits should not be present in ID 'mi_file1.2.1' !got 'offscreen', expected '0'...

Apparently the size of the arrow makes both tests fail. This is weird because the menus are small and shouldn't be overflowing anyway. This seems to be some kind of bug in the tests or arrowscrollbox.js or both...

I'll land this with arrow-dropdown-12.svg instead of arrow-dropdown-16.svg for now.

https://hg.mozilla.org/mozilla-central/rev/c5112a7573ac

(In reply to Dão Gottwald [::dao] from comment #6)

Apparently the size of the arrow makes both tests fail. This is weird because the menus are small and shouldn't be overflowing anyway. This seems to be some kind of bug in the tests or arrowscrollbox.js or both...

not sure about the test, since apparently all the test does is checking whether menuitem is visible; perhaps this arrowscrollbox.js issue: a menuitem might appear scrolled out which will make it 'offscreen' - having a screenshot would be helpful.

Anyway, I suppose no ni? request since the bug is fixed?

(In reply to alexander :surkov (:asurkov) from comment #10)

Anyway, I suppose no ni? request since the bug is fixed?

The problem still exists, I landed this with a workaround for now -- see comment 6 and comment 7.

This now looks MUCH better. Thank you!