src/vs/workbench/contrib/webview/browser/webviewElement.ts/WebviewElement/mountTo
class WebviewElement:	public mountTo(parent: HTMLElement) {
		if (!this.element) {
			return;
		}

		if (this._webviewFindWidget) {
			parent.appendChild(this._webviewFindWidget.getDomNode());
		}

		[EventType.MOUSE_DOWN, EventType.MOUSE_MOVE, EventType.DROP].forEach(eventName => {
			this._register(addDisposableListener(parent, eventName, () => {
				this.stopBlockingIframeDragEvents();
			}));
		});

		[parent, window].forEach(node => this._register(addDisposableListener(node as HTMLElement, EventType.DRAG_END, () => {
			this.stopBlockingIframeDragEvents();
		})));

		parent.appendChild(this.element);
	}