The Tiles context menu button "(...)" slightly overlaps the Section info symbol "(?)" on Windows

[SoftVision-CiprianMuresan]

https://bugzilla.mozilla.org/show_bug.cgi?id=1405296

[Affected versions]:

• Firefox 58.0a1 Build ID 20171003100226

[Affected Platforms]:

• All Windows

[Steps to reproduce]:

1. Start the browser and open a New Tab.
2. Hover the last tile in the Top Sites section.
3. Observe the context menu button.

[Expected results]:

• The context menu button does not overlap any other button.

[Actual results]:

• The context menu button slightly overlaps the section info button.

[Notes]:

• The issue is also reproducible if you hover the 3rd Top Story or the 3rd Highlight tile.
• The issue is not reproducible on Mac or Linux.
• Attached a screen shot of the issue:
  

[Mardak]

Design says use 16px as the 12px from #3562 is too small and causes problems for the arrow for #3631.

[IuliaCristescu4]

This issue is affecting the Firefox 57 build. I strongly recommend uplifting this fix in 57, too, before the merge. This will improve the feature's UX.

[Mardak]

The fix here was part of a more complex change, but we could possibly just increase the spacing to avoid the overlap for 57.