Use defaultProps instead of adding props to the svg

[lencioni]

Currently, the transformed component ends up looking something like this:

_extends({
  xmlns: 'http://www.w3.org/2000/svg',
  viewBox: '0 0 1000 1000'
}, props),

this adds the overhead of _extends. I think it might be a better to instead move these values into defaultProps on the generated component.

[kesne]

I'm not sure how that'd work out... we don't know the props ahead of time, so we can't statically set defaultProps.

Here's an example of how this all shakes out:

import MySvg from './file.svg';
const Test = () => <MySvg prop="red" />;

This turns into:

const MySvg = (props) => <svg {...props} />;
const Test = () => <MySvg prop="red" />;

Feel free to re-open if I'm mistaken.

[lencioni]

The case I'm talking about here is if the <svg> element in the SVG file itself has attributes. This plugin currently transforms it into something like this:

<svg foo="bar"></svg>

import MySvg from './file.svg';

into:

const MySvg = (props) => <svg foo="bar" {...props} />;

What I am suggesting is to instead convert these static props that are in the SVG file to defaultProps instead, like this:

const MySvg = (props) => <svg {...props} />;
MySvg.defaultProps = {
  foo: "bar",
};

[kesne]

Ah okay, that makes more sense. I can look into it, and I'd accept a PR that does that. Although I'm not super convinced that Object.assign is going to be slow enough where it matters a whole lot.