Using `canvg` breaks Safari 12

[ryanfitzer]

I added it for IE11 support, which works. But that causes Safari to error out with:

SyntaxError: The string did not match the expected pattern.

Is there a conditional I can use to add canvg? For example:

const options = someCondition ? { canvg: canvg } : {};
saveSvgAsPng( svg, 'svg.png', options );

I'm not exactly clear on what IE11 doesn't support that requires canvg to be used other than the error Rendered SVG images cannot be downloaded.

I've looked through both codebases but I haven't figured out some sort of feature test I can use to target IE11.

Any guidance would be appreciated.

[ryanfitzer]

Here's what I ended up going with:

const options = ( typeof window.navigator.msSaveBlob !== 'undefined' ) ? { canvg: canvg } : {};
saveSvgAsPng( svg, 'svg.png', options );