Migrate wicg/scroll-animations to csswg-drafts (#4334)

This migration is done via a special merge commit that includes
two unrelated git histories. This ensures we preserve the history
of edit from original specification. For more into see manual of
`git merge --allow-unrelated-histories` command.

The only changes to the scroll-animation repository content is
to move the content to scroll-animations-1 and remove a whole
bunch of unnecesary files.

Author: majido

.travis.yml

@@ -0,0 +1,22 @@
+language: generic
+sudo: required
+
+before_install:
+  - "mkdir -p ~/.npm"
+
+install:
+  - ./install-bikeshed.sh
+
+script:
+  - ./travis.sh
+
+env:
+  global:
+  - TRAVIS_COMMIT_MSG="$(git log --format=%B --no-merges -n 1)"
+  - COMMIT_USER="$(git log --format=%an --no-merges -n 1)"
+  - COMMIT_EMAIL="$(git log --format=%ae --no-merges -n 1)"
+  - ENCRYPTION_LABEL="d327396214fb"
+
+notifications:
+  email:
+  - bbirtles@mozilla.com