Documentation error on core-animation

[ebidel]

From @dgrasberger on October 29, 2014 13:30

documentation for the "fill" property correctly lists the possible values in the heading line, but incorrectly lists "forward" ( no "s" instead of "forwards") in the write-up. "forward" does not work.

https://www.polymer-project.org/docs/elements/core-elements.html#core-animation

Copied from original issue: Polymer/polymer#828

[morethanreal]

fixed in 328e99f