Bugzilla

### Beta/Release Uplift Approval Request
* **User impact if declined**: If declined, high contrast mode (HCM) users will be unable to correctly view pages with hidden elements (large impact: google searches).
* **Is this code covered by automated tests?**: Yes
* **Has the fix been verified in Nightly?**: Yes
* **Needs manual test from QE?**: No
* **If yes, steps to reproduce**: 
* **List of other uplifts needed**: None
* **Risk to taking this patch**: Medium
* **Why is the change risky/not risky? (and alternatives if risky)**: The logic for checking element visibility is a little complex (nsBlockFrame.cpp changes), but this change effects only elements that are being handled incorrectly in HCM currently. If regressions are to occur, it is likely they'll occur with other edge cases of visibility (though we've already covered `display:none`, `opacity:0`, and in this patch `visibility:hidden`)
* **String changes made/needed**:

### Beta/Release Uplift Approval Request
* **User impact if declined**: If declined, high contrast mode (HCM) users will be unable to correctly view pages with hidden elements (large impact: google searches).
* **Is this code covered by automated tests?**: Yes
* **Has the fix been verified in Nightly?**: Yes
* **Needs manual test from QE?**: No
* **If yes, steps to reproduce**: 
* **List of other uplifts needed**: None
* **Risk to taking this patch**: Medium
* **Why is the change risky/not risky? (and alternatives if risky)**: The logic for checking element visibility is a little complex (nsBlockFrame.cpp changes), but this change effects only elements that are being handled incorrectly in HCM currently. If regressions are to occur, it is likely they'll occur with other edge cases of visibility (though we've already covered `display:none`, `opacity:0`, and in this patch `visibility:hidden`)
* **String changes made/needed**:

Please ?ni me with questions :)