Add rumble support.

[MaulingMonkey]

• https://bugs.chromium.org/p/chromium/issues/detail?id=749295
• Vibrate feature for Gamepad w3c/gamepad#19
• Support Buffered Haptic Effects w3c/gamepad#39
• https://developer.mozilla.org/en-US/docs/Web/API/GamepadHapticActuator

Works in Chrome

navigator.getGamepads()[0].vibrationActuator.type == "dual-rumble"
navigator.getGamepads()[1].vibrationActuator.playEffect("dual-rumble", {
    duration: 1000, // ms
    startDelay: 0, // ms
    weakMagnitude:   1, // 0..1 (~left)
    strongMagnitude: 1, // 0..1 (~right)
});