Replaced spaces with tabs.

Check CONTRIBUTING.md, guys!

tetris/randomizers/history_6rolls.lua

@@ -4,22 +4,22 @@ local History6RollsRandomizer = Randomizer:extend()
 
 function History6RollsRandomizer:initialize()
 	self.history = {"Z", "S", "Z", "S"}
-    self.first = true
+	self.first = true
 end
 
 function History6RollsRandomizer:generatePiece()
-    if self.first then
-        self.first = false
-        return self:updateHistory(({"L", "J", "I", "T"})[math.random(4)])
-    else
-        local shapes = {"I", "J", "L", "O", "S", "T", "Z"}
-        for i = 1, 6 do
-            local x = math.random(7)
-            if not inHistory(shapes[x], self.history) or i == 6 then
-                return self:updateHistory(shapes[x])
-            end
-        end
-    end
+	if self.first then
+		self.first = false
+		return self:updateHistory(({"L", "J", "I", "T"})[math.random(4)])
+	else
+		local shapes = {"I", "J", "L", "O", "S", "T", "Z"}
+		for i = 1, 6 do
+			local x = math.random(7)
+			if not inHistory(shapes[x], self.history) or i == 6 then
+				return self:updateHistory(shapes[x])
+			end
+		end
+	end
 end
 
 function History6RollsRandomizer:updateHistory(shape)