Launcher - Window count indicators against Launcher icons display incorrectly with multiple windows across multiple workspaces

[Stewart Wilson]

Steps to replicate:
Starting from a clean slate, click on Home to open a Nautilus window on the current workspace.
The window count indicator (to the left of the Home icon on the Launcher) correctly shows 1 filled marker.
Switch to another workspace.
The window count indicator correctly shows 1 unfilled marker, to identify that there are Nautilus windows open, but not on the current workspace.
Middle-click Home in the Launcher to open a new Nautilus window on the current workspace.
The window count indicator incorrectly shows 2 filled markers, counting windows across all workspaces.

The correct behaviour is:
When there are windows open for an application, but none are on the current workspace, then the Launcher should show an unfilled window count indicator to the left of the application icon.

When there are windows open for an application on the current workspace, then the Launcher should show filled window count indicators, showing how many windows are open on the current workspace only (up to a maximum of 3 markers)