Command navigation doesn't work as expected in task terminals

[Tyriar]

Notice how for the task terminal it jumps all the way to the top on the first ctrl+up, instead of going to the most recently run task:

[meganrogge]

When I run the build task and do cmd + up, the window crashes

[Tyriar]

That's even worse 🤨

[meganrogge]

the call to get markers here returns undefined

[meganrogge]

I bet the markers are getting disposed of, so deleted from the map in bufferMarkCapability

but it looks like that wouldn't even happen since we don't set _anonymousMarkers = filtered _anonymousMarkers like we should. Could be why I see the renderer process crash?

vscode/src/vs/platform/terminal/common/capabilities/bufferMarkCapability.ts

Lines 51 to 52 in b7717f9

	marker.onDispose(() => this._anonymousMarkers.filter(m => m !== marker));
	}