Blink Principles of Web Compatibility

Good to see this bit:

> Note however that there is a substantial portion of the web which is unmaintained and will effectively never be updated (including historical archives like archive.org). It may be useful to look at how long chromium has had the behavior in question to get some idea of the risk that a lot of unmaintained code will depend on it. A breaking change being trivial to accommodate does not necessarily mean it is low risk. In general we believe in the principle that the vast majority of websites should continue to function forever.