Yes, we should not be normalizing in dart. please don't convert the camel caste to dash case.

The reason we normalize in JS is that accessing properties with `.` is easier than `[]`. So we try to make life easy for developer by converting `-` to camelCase. But in dart everything needs to be accessed with `[]` and so normalization just confuses the issue. 

Please remove it.

This CL should just ignore `data-` nothing more.