Distance between icons varies between Chrome and other browsers

Description

Steps to reproduce:
1. Open Edit mode in Firefox.
2. Note the distance between dropdown buttons in toolbars (e.g., distance between "Toggle navigation pane" and "Create content", or button width inside gadgets for "Settings", "New page", "More options", etc.).
3. Open Edit mode in Chrome.
4. Note the same distances.

Expected:
The distance should be the same.

Actual:
The distance is larger in Chrome, which has more left padding.