@Override
  public int hashCode() {
    // Assuming height, width, rarely exceed 4096 pixels, shifting
    // by 12 should provide a good hash value.
    return width << 12 + height;
  }
Similar to Point - implement locally to avoid depending on GWT.
selendroid-server/src/main/java/io/selendroid/server/android/internal/Dimension.java