%URI.DisableExternal(Resources) uses %URI.Base if %URI.Host is not available.

As part of its duties, URIDefinition determine the base URL and the host URL
of the page based on the two corresponding configuration directives. The
DisableExternal URIFilter, however, bypassed this check by directly checking
%URI.Host. This fix forwards the call through URIDefinition.

Signed-off-by: Edward Z. Yang <edwardzyang@thewritingpot.com>

tests/HTMLPurifier/URIFilter/DisableExternalTest.php

@@ -41,4 +41,11 @@ class HTMLPurifier_URIFilter_DisableExternalTest extends HTMLPurifier_URIFilterH
         );
     }
     
+    function testBaseAsHost() {
+        $this->config->set('URI', 'Base', 'http://www.example.com/foo/bar');
+        $this->assertFiltering(
+            'http://www.example.com/baz'
+        );
+    }
+    
 }