Require hosts for non-file URLs.

src/url_canon_stdurl.cc

Index: src/url_canon_stdurl.cc
===================================================================
--- src/url_canon_stdurl.cc	(revision 107)
+++ src/url_canon_stdurl.cc	(working copy)
@@ -66,10 +66,13 @@
                                     &new_parsed->username,
                                     &new_parsed->password);
 
-    // Host: always write if we have an authority (may be empty).
     success &= CanonicalizeHost(source.host, parsed.host,
                                 output, &new_parsed->host);
 
+    // Host must not be empty for standard URLs.
+    if (!parsed.host.is_nonempty())
+      success = false;
+
     // Port: the port canonicalizer will handle the colon.
     int default_port = DefaultPortForScheme(
         &output->data()[new_parsed->scheme.begin], new_parsed->scheme.len);