Escape method names in HTML

The following is invalid HTML:
<a href="Array.html#method-i-3C-3C"><code><<</code></a></p>

Incorrect:
<code><<</code>

Correct:
<code>&lt;&lt;</code>

Fixes #761

Author: natematykiewicz

lib/rdoc/markup/to_html_crossref.rb

@@ -144,7 +144,7 @@ def link name, text, code = true
       path = ref.as_href @from_path
 
       if code and RDoc::CodeObject === ref and !(RDoc::TopLevel === ref)
-        text = "<code>#{text}</code>"
+        text = "<code>#{CGI.escapeHTML text}</code>"
       end
 
       if path =~ /#/ then

test/rdoc/test_rdoc_markup_to_html_crossref.rb

@@ -89,6 +89,20 @@ def test_convert_RDOCLINK_rdoc_ref_method_percent
     assert_equal para("<a href=\"C1.html#method-c-25\"><code>C1::%</code></a>"), result
   end
 
+  def test_convert_RDOCLINK_rdoc_ref_method_escape_html
+    m = @c1.add_method RDoc::AnyMethod.new nil, '<<'
+    m.singleton = false
+
+    result = @to.convert 'rdoc-ref:C1#<<'
+
+    assert_equal para("<a href=\"C1.html#method-i-3C-3C\"><code>C1#&lt;&lt;</code></a>"), result
+    m.singleton = true
+
+    result = @to.convert 'rdoc-ref:C1::<<'
+
+    assert_equal para("<a href=\"C1.html#method-c-3C-3C\"><code>C1::&lt;&lt;</code></a>"), result
+  end
+
   def test_convert_RDOCLINK_rdoc_ref_method_percent_label
     m = @c1.add_method RDoc::AnyMethod.new nil, '%'
     m.singleton = false