This change takes all existing WebIDL files in the repo that had
definition lines without four leading spaces, and fixes them so they
have four leading spaces.
(cherry picked from commit 51528ec6779202747cc3b99d3b77772a124a0b47)
The intent is to use these to autogenerate prototype declarations for
Window and WorkerGlobalScope classes.
And the spec links are just nice to have :^)