Merge pull request #2510 from Tyriar/line_one

Set disposed marker line to -1

src/common/buffer/Marker.ts

@@ -29,6 +29,7 @@ export class Marker extends Disposable implements IMarker {
  return;
  }
  this.isDisposed = true;
+ this.line = -1;
  // Emit before super.dispose such that dispose listeners get a change to react
  this._onDispose.fire();
  }