embedded CSS regression riot@5 to riot@6 and later

[qlbit-com]

1. Describe your issue:

I'm having strange regression in compiled code which has embedded CSS.
It works when compiler riot@5 is used, and fails with compiler riot@6 , see plunker below.

code is a menu component which uses onMouseOver to change the display style on sibling element to show\hide nested menu items.

Please advise if that is improper technique.

2. Can you reproduce the issue?
   https://plnkr.co/edit/1GSWeSbs47tSMUHg

3. On which browser/OS does the issue appear?
   win10\Chrome , win10\Edge, win10\Opera

4. Which version of Riot does it affect?
   works with riot5 compiler, fails with riot6 compiler.

5. How would you tag this issue?

• Question
• Bug\regression
• Discussion
• Feature request
• Tip
• Enhancement
• Performance

[qlbit-com]

to reproduce in plunker in index.html change:
<script type="text/javascript" src="https://unpkg.com/riot@5/riot+compiler.min.js"></script>
to
<script type="text/javascript" src="https://unpkg.com/riot@7/riot+compiler.min.js"></script>

[qlbit-com]

when testing with webpack:
regression observed between compiler version 5.4.2 and 6.0.0,
all later versions of the compiler between 6.0.0 and 6.4.1 showing this issue.

[GianlucaGuarini]

Thank you for reporting it. This issue is related to #2967

[GianlucaGuarini]

Fixed in riot@7.1.0 thank you for submitting this issue