Correctly set initiated_in_secure_context on requests from shared/service workers,

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/foreign-fetch-helper-script.js

+function handle_message(e) {
+  fetch(e.data.url)
+    .then(response => response.text())
+    .then(text => e.ports[0].postMessage('Success: ' + text))
+    .catch(error => e.ports[0].postMessage('Error: ' + error));
+}
+
+self.onmessage = handle_message;
+self.onconnect = e => {
+  e.ports[0].onmessage = handle_message;
+};