HTTPlug icon in Profiler bar is not displayed in some browsers

[bocharsky-bw]

Q	A
Bug?	yes
New Feature?	no
Version	Latest stable release (v1.14.0)

Actual Behavior

In Chrome / Safari / Opera - no icon:

Expected Behavior

In Firefox the icon is displayed:

Steps to Reproduce

Just open Symfony Web Debug profiler.

Possible Solutions