make sync-default-gems GEM=irb

from ruby/irb@89e9add.

This adds syntax highlight support for Module on inspect.

In addition to that, I'm adding a trailing space in test_color.rb for
testing ruby-commit-hook's auto-style.

lib/irb/color.rb

@@ -46,7 +46,7 @@ def colorable?
       end
 
       def inspect_colorable?(obj)
-        if obj.is_a?(Class) && obj.name
+        if obj.is_a?(Module) && obj.name
           return true
         end
 

test/irb/test_color.rb

@@ -55,6 +55,7 @@ def test_inspect_colorable
         /reg/ => true,
         Object.new => false,
         Struct => true,
+        Test => true, 
         Struct.new(:a) => false,
         Struct.new(:a).new(1) => false,
       }.each do |object, result|