LONDON (Reuters) - Easyjet will return to London's bluechip FTSE 100 index from Dec. 23, along with food delivery firm Just Eat , after the latest quarterly review, operator FTSE Russell said on Wednesday.The budget airline's shares have rallied 43% in the last three months, helping them secure a place again after being demoted in June.Miner Fresnillo and insurer Hiscox will be relegated.The demotions were widely expected based on the recent closing prices of the stocks that saw them ranked..