The change in 7fe83e4b8b7d62b0b8b31971389599afaf0a27ca broke method
contract from `IStatusLineManager.getProgressMonitor()`. It was
originally stating "returns monitor", not it says "creates new monitor".

So the browser listener is not able now to use
`IStatusLineManager.getProgressMonitor()` directly and has to keep a
local monitor instance.

Fixes https://github.com/eclipse-platform/eclipse.platform.ui/issues/1398