As the title implies, setting foo.style.contain = none/style; has no visual effect.
Created attachment 463124 [details] Patch
Created attachment 463126 [details] Patch
<rdar://problem/101602675>
Created attachment 463312 [details] Patch
This patch modifies the imported WPT tests. Please ensure that any changes on the tests (not coming from a WPT import) are exported to WPT. Please see https://trac.webkit.org/wiki/WPTExportProcess
*** Bug 260483 has been marked as a duplicate of this bug. ***