Remove unused prefix argument from http_url methods

Since their prefix argument is always nil, we can stop passing it
and simplify the methods accordingly.

Author: st0012

lib/rdoc/code_object/class_module.rb

@@ -634,7 +634,7 @@ def parse comment_location
   # Path to this class or module for use with HTML generator output.
 
   def path
-    http_url(nil)
+    http_url
   end
 
   ##

lib/rdoc/code_object/context.rb

@@ -973,10 +973,10 @@ def fully_documented?
   ##
   # URL for this with a +prefix+
 
-  def http_url(prefix)
+  def http_url
     path = name_for_path
     path = path.gsub(/<<\s*(\w*)/, 'from-\1') if path =~ /<</
-    path = [prefix] + path.split('::')
+    path = path.split('::')
 
     File.join(*path.compact) + '.html'
   end

lib/rdoc/code_object/top_level.rb

@@ -173,10 +173,8 @@ def hash
   ##
   # URL for this with a +prefix+
 
-  def http_url(prefix)
-    path = [prefix, @relative_name.tr('.', '_')]
-
-    File.join(*path.compact) + '.html'
+  def http_url
+    @relative_name.tr('.', '_') + '.html'
   end
 
   def inspect # :nodoc:
@@ -246,7 +244,7 @@ def page_name
   # Path to this file for use with HTML generator output.
 
   def path
-    http_url(nil)
+    http_url
   end
 
   def pretty_print q # :nodoc:

test/rdoc/test_rdoc_top_level.rb

@@ -156,10 +156,10 @@ def test_hash
   end
 
   def test_http_url
-    assert_equal 'prefix/path/top_level_rb.html', @top_level.http_url('prefix')
+    assert_equal 'path/top_level_rb.html', @top_level.http_url
 
     other_level = @store.add_file 'path.other/level.rb'
-    assert_equal 'prefix/path_other/level_rb.html', other_level.http_url('prefix')
+    assert_equal 'path_other/level_rb.html', other_level.http_url
   end
 
   def test_last_modified