text: // TODO(dvoytenko): Remove once Closure adds this extern.
  // See: https://github.com/google/closure-compiler/issues/2134
  // See: https://www.w3.org/TR/web-animations/
  
  /*
   * Copyright 2016 The Closure Compiler Authors
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  
  /**
   * See https://developer.mozilla.org/en-US/docs/Web/API/Animation
   * @interface
   */
  class WorkletAnimation {
    constructor() {
    }
  
    /**
     * Starts or resumes playing of an animation, or begins the animation again
     * if it previously finished.
     */
    play() {}
  
    /**
     * Clears all keyframeEffects caused by this animation and aborts its
     * playback.
     */
    cancel() {}
  
    /**
     * Seeks either end of an animation, depending on whether the animation is
     * playing or reversing.
     */
    finish() {}
  
    /**
     * Suspends playing of an animation.
     */
    pause() {}
  
    /**
     * Reverses playback direction, stopping at the start of the animation.
     * If the animation is finished or unplayed, it will play from end to
     * beginning.
     */
    reverse() {}
  }
  
  
  /**
   */
  class ScrollTimeline {
    constructor() {
    }
  }
  
  /**
   * @extends {CSSRule}
   * @see https://drafts.csswg.org/css-conditional-3/#the-csssupportsrule-interface
   */
  class CSSSupportsRule {
    constructor() {
      /** @type {string} */
      this.conditionText;
      /** @type {!CSSRuleList} */
      this.cssRules;
    }
  }
  
  /**
   * @see https://developers.google.com/web/updates/2018/10/animation-worklet
   * @type {!Worklet|undefined}
   */
  CSS.animationWorklet;
  