Added schemeless URL testing

TODO.txt

@@ -1,7 +1,5 @@
 - [CHECKING] SF #2784996
   Incorrect URL fragment handling
-- [TEST] Test protocol-independent links like
-  <img src="//example.com/logo.png"/>
 - [CMDLINE] SF #2770077
   Titles of bookmarks with umlauts are not printed correctly.
 - [GUI] Add more context menu actions:

tests/checker/data/http.html

@@ -3,6 +3,7 @@ Just some HTTP links
 <a href="http://localhost:8001/">ok</a>
 <a href="http:/localhost:8001/">one slash</a>
 <a href="http:localhost:8001/">no slash</a>
+<a href="//localhost:8001/">no scheme</a>
 <a href="http://">no url</a>
 <a href="http:/">no url, one slash</a>
 <a href="http:">no url, no slash</a>

tests/checker/data/http.html.result

@@ -56,6 +56,12 @@ name no slash
 warning Base URL is not properly normed. Normed URL is http:///localhost%%3A8001/.
 error
 
+url //localhost:8001/ (cached)
+cache key http://localhost:8001/
+real url http://localhost:8001/
+name no scheme
+valid
+
 url http://
 cache key http://
 real url http://