Revert "Update the TIP formatter to handle multiline tips"

This reverts commit e3dbe66e196069fde7d3ff118bd25a03184915fa.

Reason: Code changes are not allowed in docrails.

railties/guides/rails_guides/textile_extensions.rb

@@ -15,11 +15,10 @@ def notestuff(body)
     end
 
     def tip(body)
-      body.gsub!(/^TIP[.:](.*?)(\n\Z|\n\n+|\Z)/m) do |m|
+      body.gsub!(/^TIP[.:](.*)$/) do |m|
         result = "<div class='info'><p>"
         result << $1.strip
         result << '</p></div>'
-        result << $2 if $2
         result
       end
     end

railties/test/guides/textile_extionsions_test.rb

@@ -1,37 +0,0 @@
-require 'isolation/abstract_unit'
-require 'guides/rails_guides/textile_extensions'
-
-class TextileExtensionsTest < Test::Unit::TestCase
-  include ActiveSupport::Testing::Isolation
-  include RailsGuides::TextileExtensions
-  
-  test "tips can handle a single line" do
-    expected_output = "<div class='info'><p>this is a single line tip</p></div>"
-    assert_equal expected_output, tip('TIP. this is a single line tip')
-  end
-
-  def setup
-    @multi_line_tip = "This is a multi-line tip.\n" +
-      "Isn't it fantastic?"
-  end
-
-  test "tips can handle a multi-line tip" do
-    expected_output = "<div class='info'><p>#{@multi_line_tip}</p></div>"
-
-    assert_equal expected_output, tip("TIP. #{@multi_line_tip}")
-  end
-
-  test "muli-line tips handles text before and after the tip" do
-    pre_line = "This is text before hand.\n\n"
-    post_line = "\n\nThis is some text after"
-    input_text = pre_line +
-      "TIP. #{@multi_line_tip}" +
-      post_line
-
-    expected_output = pre_line +
-      "<div class='info'><p>#{@multi_line_tip}</p></div>" +
-      post_line
-
-    assert_equal expected_output, tip(input_text)
-  end
-end