Implement: https://rawgit.com/w3c/webcomponents/construction/spec/custom/index.html#unresolved-element-pseudoclass The :unresolved pseudo-class [CSS3-SELECTORS] must match all custom elements whose custom element constructor has not yet been invoked. <rdar://problem/24923698>
Created attachment 273171 [details] WIP
The spec has been updated to now define :defined instead: https://w3c.github.io/webcomponents/spec/custom/#the-defined-element-pseudo-class-defined
Created attachment 273549 [details] Adds the support
Created attachment 273550 [details] Fixed change logs
r=me
Committed r197952: <http://trac.webkit.org/changeset/197952>