PASSTHROUGH box does not disappear on re-enable

[troyp]

When disabling Vrome with C-z, a PASSTHROUGH box appears. However, when re-enabling with C-Esc (or enable_vrome_key), the box remains. Multiple disable and re-enable operations consistently leave the box unchanged. It can be dismissed by clicking on it, or by summoning and dismissing another Vrome box (eg search box).

Notes:

• Chrome 35.0.1916.153
• I've tested with two profiles: one with many extensions, the other with only Singlefile, DuckDuckGo and XMarks extensions