Inject inline-script logger scriptlet at document_end

Feedback from related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/343#issuecomment-449529429

src/js/ublock.js

@@ -559,7 +559,7 @@ var matchBucket = function(url, hostname, bucket, start) {
     vAPI.tabs.injectScript(tabId, {
         frameId: frameId,
         file: '/js/scriptlets/inlinescript-logger.js',
-        runAt: 'document_start'
+        runAt: 'document_end'
     });
 };