SYDNEY (Reuters) - Global stocks were sailing into Christmas on a sea of red on Friday, as the threat of a U.S. government shutdown and of further hikes in U.S. borrowing costs inflamed investor unease over the economic outlook. A man walks past in front of a stock quotation board showing the price of the SoftBank Corp. and Nikkei share average outside a brokerage in Tokyo, Japan December 19, 2018.