Tabs don't un-suspend when viewed by closing adjacent tabs

[jaydge]

The issue originally reported in #550 is back it seems. Screen capture video here: https://www.screencast.com/t/OOfIGYkb.

To replicate:

1. Set your options to auto-suspend tabs after 20 seconds (short just for testing), and set tabs to auto-unsuspend when viewed. Screenshot of options: https://www.screencast.com/t/KQ2p3XHnr
2. When you click or CTRL+TAB over to a tab, it unsuspends fine, but when you close a neighboring active tab which by default reveals a suspended tab, the suspended tab doesn't auto-unsuspend until user interaction such as clicking it or CTRL+TAB back and forth to it occurs.

Seen on Chrome Version 61.0.3163.100 (Official Build) (64-bit), on Windows 7 Professional SP1.

[deanoemcke]

This is a duplicate of: #519
This was intentionally changed, but due to user feedback it will be reverted back to how it used to work in the upcoming release (v7.x).