Favicon invisible on dark background

[DonEstefan]

This is a public issue tracker.

Be sure that your description and screenshots not contain any personal or company info.

Describe the bug:

The Favicon is not visible on tabs with dark background color. This is especially annoying when using a combination of the default firefox theme and pinned tabs (where you see no text but only the favicon)

To Reproduce:

1. Open phonebook in firefox (browser with dark background for tabs)
2. open a second empty tab
3. Look at the phonebook favicon (dark background in firefox is used only for tabs that are not currently active)

Expected behavior:

Id like to see the favicon clearly independent of the current background color. This is much needed for use in pinned Tabs where you see no text but only favicon in the tab heading.

Screenshots:

[mr-woodapple]

Not fixed, as the fix was reverted.