The HTML Origin spec has two similar but slightly different concepts of
origin equality: "same origin" and "same origin-domain". Let's be
explicit with the naming here :^)
Also add spec comments.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *