Consider removing png assets for some logos?

[alexgibson]

The NPM package that this repo publishes is now a whooping 28MB. I'm not sure if there's a limit to the size of an NPM package, but either way this is quite a lot of bandwidth to be pulling down every time Protocol gets built.

For some logo variations, such as Pocket and Mozilla VPN, I'm not sure of anywhere (at leasty on bedrock) where we don't use SVG today. The only real exception seems to be the Firefox logo, where a PNG can often compress smaller than an SVG.

This is open for discussion, but should we consider culling some of the more bandwidth heavy PNG variations that are not really well used? This of course would be a breaking change and a major version bump.

[maureenlholland]

Pausing work on https://github.com/mozilla/protocol-assets/issues/61 and https://github.com/mozilla/protocol-assets/issues/60 to do a quick audit on what PNGs we're actually using here.

Likely still need PNG for Firefox logo but VPN and Pocket could be SVG-only.

[maureenlholland]

Considering major breaking change to remove PNG assets for the following reasons:

• all the size and high-res variations are difficult to maintain
• would reduce the size of the NPM package considerably
• high-res PNGs are often larger than the SVGs and high res displays are becoming more common
• logos are flat enough that even when PNG is smaller, it's not by much (with notable exception of Dev Firefox at the moment)

To address before this change:

• do we keep a fallback PNG for older IE browsers that do not support SVG? do we show alt text in these cases?
• Protocol logo and wordmark mixins need to look for SVG paths
• add SVG wordmark variations (horizontal, vertical, white, stack)
• do we keep og.png? does opengraph support SVG?

[maureenlholland]

Closed with https://github.com/mozilla/protocol-assets/pull/75