remove double_tap processing code in keyboard

frontend/ui/widget/keyboard.lua

@@ -69,12 +69,6 @@ function VirtualKey:init()
 					range = self.dimen,
 				},
 			},
-			DoubleTapSelect = {
-				GestureRange:new{
-					ges = "double_tap",
-					range = self.dimen,
-				},
-			},
 		}
 	end
 end
@@ -88,16 +82,6 @@ function VirtualKey:onTapSelect()
 	return true
 end
 
-function VirtualKey:onDoubleTapSelect()
-	self[1].invert = true
-	if self.callback then
-		self.callback() -- once
-		self.callback() -- twice
-	end
-	UIManager:scheduleIn(0.02, function() self:invert(false) end)
-	return true
-end
-
 function VirtualKey:invert(invert)
 	self[1].invert = invert
 	UIManager.update_region_func = function()