Simplify float literal mutator

* Adjust flay score

config/flog.yml

@@ -1,2 +1,2 @@
 ---
-threshold: 15.6
+threshold: 14.4

lib/mutant/mutator/literal/float.rb

@@ -15,12 +15,22 @@ module Mutant
         def dispatch
           emit_nil
           emit_values(values)
-          emit_safe(infinity)
-          emit_safe(negative_infinity)
-          emit_safe(nan)
+          emit_special_cases
           emit_new { new_self(Random.float) }
         end
 
+        # Emit special cases
+        #
+        # @return [undefined]
+        #
+        # @api private
+        #
+        def emit_special_cases
+          [infinity, negative_infinity, nan].each do |value|
+            emit_safe(value)
+          end
+        end
+
         # Return values to test against
         #
         # @return [Array]