Summary

Replaced the is(':visible') check because it prevented rendering of the charts placed in containers that are hidden (like Otter Tabs Block)

Screenshot

Testing (from linked issue)

1. Install Tabby Responsive Tabs
2. Copy this code and paste it on a page:

[tabby title="First Tab"]

This is the content of the first tab.

[tabby title="Second Tab"]

This is the content of the second tab.
[tabby title="Third Tab"]

This is the content of the third tab.

[tabbyending]

1. Insert one of the Visualizer's shortcodes inside one of the tabs.
2. Publish and check the page

Do the same for Otter:

1. Add the Tabs block
2. Inside one of the tabs, insert a chart's shortcode

Close #1072