LONDON (Reuters) - Britain's Heathrow Airport reported a 4.6% rise in annual earnings boosted by higher passenger numbers, and said that it is set to be overtaken as Europe's busiest airport, strengthening the case for expansion. Heathrow reported adjusted core earnings (EBITDA) of 1.9 billion pounds for 2019, up 4.6%, on revenues that rose 3.4% to 3.1 billion pounds. The airport, the largest in Britain, has a project to build a third runway, which it says it can do without compromising..