WASHINGTON, Dec 15 (Reuters) - Speaker Nancy Pelosi said on Thursday she had yet to decide whether the U.S. House of Representatives will join the Senate in backing legislation to bar federal government employees from using Chinese-owned TikTok on government-owned devices. "We're checking with the administration - just in terms of language - not in terms of being opposed to the idea," Pelosi told reporters a day after the Senate vote. "I don't know that that will be on the agenda next week, but it's very, very important." The House would need to pass the Senate bill before next week's...