[5.8 REG] Active tab gets gray when background tab is closed

Since 5.8 there is a bug in the Demo Browser Example:
If you load the website hrs.de and click on a link which opens in a new tab i.e. holidays.hrs.de in the middle of the hrs home page. The new tab comes in foreground. The old tab goes to background. If you close the old tab by clicking the red cross in the tabbar, the background tab closes and the foreground tab gets completely gray. Even a refresh by F5 doesn't bring the website back.
I checked with --remote-debugging-port that the DOM of the hidden website is still alive. The JavaScript is still executed. It is just invisible.
This bug is not reproducible with Ctrl+clicking for opening a link in a new tab.
The behavior was observed in release and debug builds. There is no such bug in 5.7.