AppIcon: Draw running dot above the overview icon
app-well-app-running-dot above its sibling
overview-icon. Before this, the icon background, which is used e.g. for the
:hover effect, was drawn above the running dots, affecting in their appearance.
This was mainly an issue for user themes, that may use solid background-color for e.g.
overview-icon:hover, which unintentionally hides the running dot completely.
For default shell theme, this corrects the running-dot color for hovered overview-icon, that appeared in slightly different color than other running-dots, due to the translucent overview-icon background being drawn above it: