Cleanup redundant code in Sunburst chart

[kum-deepak]

While working on some other refactors, I came across this.

Removing this code does not seem to have any impact. Test cases still pass, the charts work. In addition, reading the code makes the believe that the BaseMixin's implementation covers the needs of this chart.

[gordonwoodhull]

It's apparently a performance improvement: 601e723

Probably to avoid the second case in the loop of the default filter handler:

dc.js/src/base/base-mixin.js

Lines 24 to 34 in a393078

	dimension.filterFunction(d => {
	for (let i = 0; i < filters.length; i++) {
	const filter = filters[i];
	if (filter.isFiltered && filter.isFiltered(d)) {
	return true;
	} else if (filter <= d && filter >= d) {
	return true;
	}
	}
	return false;
	});

Correct fix for the workaround you propose removing would be

            if (filter.isFiltered) {
                if(filter.isFiltered(d)) {
                    return true;
                }
            } else if (filter <= d && filter >= d) {
                return true;
            }

I don't think we ever want a filter object which has .isFiltered and should be second-guessed if it returns false.

[kum-deepak]

Thanks! Makes sense.

[kum-deepak]

I am working on an experimental PR to refactor filters, dimensions, and groups. I will commit an initial version and future thoughts soon.

[gordonwoodhull]

Cool, thanks @kum-deepak!