Add fastdom js dependency

[mistercrunch]

The nvd3 docs say that it if the fastdom library is present it makes use
of it.

"Including Fastdom in your project can greatly increase the performance
of the line chart (particularly in Firefox and Internet Explorer) by
batching DOM read and write operations to avoid layout thrashing. NVD3
will take advantage of Fastdom if present."

Annectodal evidence refreshing a 4*nvd3 slices dashboard before/after fastdom

[kristw]

fastdom has never been imported into the js code, so window.fastdom does not exist and nvd3 in superset did not get the benefits.

From nvd3 https://github.com/novus/nvd3/blob/master/src/dom.js

nv.dom.write = function(callback) {
	if (window.fastdom !== undefined) {
		return fastdom.mutate(callback);
	}
	return callback();
};

[mistercrunch]

Oh makes sense, I assumed the lib could just be discovered and used as it would in Python, but that's actually not the case with JS/Webpack. So I'm guessing we have to import it explicitly.