Ref #13483: Cherry-pick tests from master ea5c22ec12e6a548b1ec2d7b0dcd9f71bea8d5dd
Fix #13855: line-height animations. Close gh-1265.
(cherry picked from commit 3971c2ebb2e6729fe80bac4ee7b91bc02f26486f)
Fix #13835: classes separated by form feed
(cherry picked from commit d8a35011ec05ed3493a85c1bd699902893cd437c)