Improve performance of Multibyte::Utils.

Replace explicit for-loops by faster enumeration methods.

[#3158 state:committed]

activesupport/lib/active_support/multibyte/utils.rb

@@ -26,11 +26,11 @@ def self.verify(string)
     else
       def self.verify(string)
         if expression = valid_character
-          for c in string.split(//)
-            return false unless expression.match(c)
-          end
+          # Splits the string on character boundaries, which are determined based on $KCODE.
+          string.split(//).all? { |c| expression.match(c) }
+        else
+          true
         end
-        true
       end
     end
 
@@ -49,9 +49,8 @@ def self.clean(string)
     else
       def self.clean(string)
         if expression = valid_character
-          stripped = []; for c in string.split(//)
-            stripped << c if expression.match(c)
-          end; stripped.join
+          # Splits the string on character boundaries, which are determined based on $KCODE.
+          string.split(//).grep(expression).join
         else
           string
         end