message: fix(content): fix iframe flickering in Chrome
diff: border-radius: 50%;
  background: orange;
  animation: panel-DictItem_Loader-shift 2s linear infinite;
  - will-change: transform, opacity;
  &:nth-child(2) {
  animation-delay: -0.4s;
  fill: #000;
  }
  +/**
  + * remove GPU acceleration which might casue iframe flickering in Chrome 66
  + * @todo add back after Chrome 68
  + */
  @keyframes panel-DictItem_Loader-shift {
  - 0% { transform: translateX( 0 ); opacity: 0; }
  - 10% { transform: translateX( 30px); opacity: 1; }
  - 90% { transform: translateX( 80px); opacity: 1; }
  - 100% { transform: translateX(110px); opacity: 0; }
  + 0% { left: 0 ; background-color: rgba(255, 165, 0, 0); }
  + 10% { left: 30px; background-color: rgba(255, 165, 0, 1); }
  + 90% { left: 80px; background-color: rgba(255, 165, 0, 1); }
  + 100% { left: 110px; background-color: rgba(255, 165, 0, 0); }
  }
  