Created attachment 66913 [details]
Test case for -webkit-line-clamp and visibility hidden issue
When an element with visibility: hidden and -webkit-line-clamp: [anything] is appended to the DOM, the line clamp is not respected, even after setting visibility: visible or removing the visibility setting altogether. Note that the problem really seems to be that -webkit-line-clamp is ignored when rendering an element with visibility: hidden, not when making it visible (although the problem continues to persist then).
Test case attached.
Blah blah blah
1. Remove #container
2. Set visibility: hidden on #container
3. Append #container to #root
4. Remove visibility: hidden on #container
This also works if the element you remove and set visibility on is #clamped instead of #container. Just wanted to illustrate that it could be any node up the tree.
I can confirm the existence of this bug in Chrome Version 28.0.1500.71.
Definitely seeing it on 39.0.2171.95: both desktop and mobile