A stale layout root is set as an input element in WebKit in Google Chrome before Blink M13 when a child of a keygen with autofocus is accessed.
trac.webkit.org/browser/trunk/Source/WebCore/rendering/RenderObject.h?rev=86705
trac.webkit.org/changeset/86976
trac.webkit.org/changeset/90568
trac.webkit.org/changeset/90848
bugs.chromium.org/p/chromium/issues/detail?id=83672
bugs.webkit.org/show_bug.cgi?id=57091
code.google.com/p/chromium/issues/detail?id=82063