Make CSSKeyframesRule function arguments non-optional

http://dev.w3.org/csswg/css-animations/#interface-csskeyframesrule

insertRule() is not in the spec, but as an alias of appendRule() it's
best to keep them in sync.

Making the findRule() return type nullable doesn't change the generated
code.

Review URL: https://codereview.chromium.org/790303002

git-svn-id: svn://svn.chromium.org/blink/trunk@186895 bbb929c8-8fbe-4397-9dbb-9b2b20218538
3 files changed
tree: 33447ff649070f98cb6b4e71abada93638071409
  1. third_party/