Dec 10 (Reuters) - Shares of Airbnb Inc were set to soar in the biggest U.S. stock market debut of 2020 on Thursday, capping a record year for new listings that has seen investors flock to tech darlings. At 10:12 a.m. ET, the home rental firm’s shares were indicated to open at $149, more than double an upwardly revised initial public offering price of $68 apiece that raised $3.5 billion for the company. (Reporting by Noor Zainab Hussain in Bengaluru; Editing by Sriraj Kalluvila and Shounak Dasgupta)