Include the document URL in the load_time_data.js expectation failures.

ui/webui/resources/js/load_time_data.js

Index: ui/webui/resources/js/load_time_data.js
diff --git a/ui/webui/resources/js/load_time_data.js b/ui/webui/resources/js/load_time_data.js
index ee3d497d654cbc1d6729f96f83d5426039896992..33b388094bc5cbdd3af870c9eef9c531af814f29 100644
--- a/ui/webui/resources/js/load_time_data.js
+++ b/ui/webui/resources/js/load_time_data.js
@@ -118,8 +118,10 @@ var loadTimeData;
    * @param {string} message The message to display if the check fails.
    */
   function expect(condition, message) {
-    if (!condition)
-      console.error(message);
+    if (!condition) {
+      console.error('Unexpected condition on ' + document.location.href + ': ' +
+                    message);
+    }
   }
 
   /**