When an input type="search" is directly or inherits the style visibility: hidden the "cancel" button of the field still appears. See the attached html file as an example, hidden_field.html Note: This has been observed in the latest nightly build.
Created attachment 41537 [details] Hidden field sample markup
<rdar://problem/7321586>
Looks like this has been fixed. I cannot repro on ToT.
*** This bug has been marked as a duplicate of bug 65001 ***