wip: foregin eq from comparapable comp type.

This commit adds the framework for "comparable components". This allows
complete sealing of bump-allocated properties types, and a comparison method
that performs a "safe" cast without transmute. This lets us completely erase types
but still be able to perform partialeq over render frames

packages/web/examples/weather.rs

@@ -45,3 +45,4 @@ fn main() {
         })
     }));
 }
+