parser: don't treat floating properties as errors
parser: don't treat floating properties as errors

The following case was made impossible:

   subcomponents {
      property: value;
      component { /* ... */ }
   }

We currently have no properties in this block, but I can see no reason
why we couldn't have any some day. So, the parser will not
inconditionnaly throw an error in these cases.

subcomponent/subcomponent,subcomponent/subcomponent