Nov 12 (Reuters) - Walt Disney Co reported a smaller-than-expected drop in fourth-quarter revenue on Thursday, calming worries of a big impact from the COVID-19 pandemic on its theme parks and movie studio businesses. Overall revenue fell about 23% to $14.71 billion in the quarter ended Oct. 3, above analysts’ average estimate of about $14.2 billion, according to Refinitiv IBES data.