servo: Merge #13448 - Fix doc build (fixes #12964) (from Manishearth:fx-doc); r=Ms2ger

r? @Ms2ger

Source-Repo: https://github.com/servo/servo
Source-Revision: 2474393d15b4e6259bdcf366d3423c3a6cd2eaac

servo/etc/ci/upload_docs.sh

@@ -18,7 +18,7 @@ cd "$(dirname ${0})/../.."
 # etc/doc.servo.org/index.html overwrites $(mach rust-root)/doc/index.html
 cp etc/doc.servo.org/* target/doc/
 
-python components/style/properties/build.py servo html
+python components/style/properties/build.py servo html regular
 
 cd components/script
 cmake .