Fix relative links in the PDF version

Closes whatwg/html#9097.

Also contains a drive-by fix to remove the step which pulls down pdfsizeopt, which we no longer use after 18b6e24.

Author: domenic

ci-build/docker-build.sh

@@ -27,7 +27,6 @@ function main {
   # Build the Docker image, using Docker Hub as a cache. (This will be fast if nothing has changed
   # in html-build or its dependencies).
   docker pull whatwg/wattsi
-  docker pull ptspts/pdfsizeopt
   docker pull "$docker_hub_repo" || true
   docker build --cache-from "$docker_hub_repo" --tag "$docker_hub_repo" .
 }

ci-build/inside-container.sh

@@ -14,6 +14,15 @@ echo "Running conformance checker..."
 java -Xmx1g -jar ./vnu.jar --skip-non-html "$HTML_OUTPUT"
 echo ""
 
+# The build output contains some relative links, which will end up pointing to
+# "https://0.0.0.0:$PDF_SERVE_PORT/" in the built PDF. That's undesirable; see
+# https://github.com/whatwg/html/issues/9097. Our hack is to replace such
+# relative links like so. Note: we can't just insert a <base> or use Prince's
+# --baseurl option, because that would cause Prince to crawl the actual live
+# files for subresources, missing any updates to them we made as part of this
+# change.
+sed 's| href=/| href=https://html.spec.whatwg.org/|g' "$HTML_OUTPUT/index.html" > "$HTML_OUTPUT/print.html"
+
 # Serve the built output so that Prince can snapshot it
 # The nohup/sleep incantations are necessary because normal & does not work inside Docker:
 # https://stackoverflow.com/q/50211207/3191
@@ -24,4 +33,6 @@ echo ""
 
 echo ""
 echo "Building PDF..."
-PATH=/whatwg/prince/bin:$PATH prince --verbose --output "$HTML_OUTPUT/print.pdf" "http://0.0.0.0:$PDF_SERVE_PORT/"
+PATH=/whatwg/prince/bin:$PATH prince --verbose --output "$HTML_OUTPUT/print.pdf" "http://0.0.0.0:$PDF_SERVE_PORT/print.html"
+
+rm "$HTML_OUTPUT/print.html"