A significant increase in revenue in the past quarter has restored Wall Street’s faith in the photo app Snapchat. The shares of parent company Snap jumped by more than a quarter in after-hours trading on Thursday. Three months ago, the share price had plummeted by more than 3% following the disappointment of that quarter’s figures. Now, Snap’s revenue rose by 21% year-on-year to just under $1.19 billion in the past quarter. Prior to this, Snapchat’s once rapidly growing advertising business had weakened because advertising dollars had increasingly flowed to heavyweights such as Google and Face…