Negative animation delay doesn't work

[alex88]

1. Which version of PhantomJS are you using? Tip: run phantomjs --version.
   2.1.1
2. What steps will reproduce the problem?
   1. Open http://jsfiddle.net/9Ryvs/5473/
   2. Look at the box
3. Which operating system are you using?
   OSX 10.12.3
4. Did you use binary PhantomJS or did you compile it from source?
   Binary from homebrew
5. Please provide any additional information below.
   In chrome and safari the box is slighty rotated, as it is after 1.5 seconds from the start of the animation, which is what the negative animation delay is about, in phantomjs screenshot instead, the box is in it's initial position

[stale]

Due to our very limited maintenance capacity, we need to prioritize our development focus on other tasks. Therefore, this issue will be automatically closed (see #15395 for more details). In the future, if we see the need to attend to this issue again, then it will be reopened. Thank you for your contribution!