src/vs/workbench/contrib/webviewPanel/browser/webviewEditorInput.ts/WebviewInput/transfer
class WebviewInput:	protected transfer(other: WebviewInput): WebviewInput | undefined {
		if (this._hasTransfered) {
			return undefined;
		}
		this._hasTransfered = true;
		other._webview = this._webview;
		return other;
	}