Cannot close pane with cmd+w when tabs are disabled.

[cleversprocket]

• VSCode Version: 1.4.0
• OS Version: OSX 10.10.5

Steps to Reproduce:

1. Disable Tabs by setting the rule "workbench.editor.showTabs": false in User settings settings.json
2. Select a file to edit with cmd+p.
3. Repeat step 2 with several different files.
4. Open a new editor pane with cmd+2.
5. Use step 2 in the new pane to open a file for editing.
6. Repeat step 3 in the new pane.
7. Attempt to close the new pane with cmd+w.

Expected Results:
The pane closes using cmd+w.

Actual Results:
cmd+w just closes the the file but the pane (or possibly the editor group?) remains open.

Notes:
This behavior started happening after Tabs was introduced. I've tried workbench.action.closeAllEditors and workbench.action.closeEditorsInGroup and the pane still will not close.

[bpasero]

See #6605

[cleversprocket]

@bpasero I mentioned in the Notes section of the bug that using workbench.action.closeEditorsInGroup does not work.

[bpasero]

@cleversprocket can you demo this in a video? or screenshots?