[1.0] ::before / ::after psudo selectors in a custom-style

[blasten]

I came across with this issue while using ::before

<style is="custom-style">
   span::before {
     content: "->";
     color: red;
   }
</style>

The shim will create the selector span::before:not([style-scope]):not(.style-scope), but the browser is expecting span:not([style-scope]):not(.style-scope)::before

[trading-peter]

I wrote a quick and dirty work-a-round-hack to fix this till it's implemented properly.
See 8f26767
Will see if it holds... This is really annoying if you work with some icon font like font awesome.