cros: Dump login/lock/oobe JS error stack traces to logs.

chrome/browser/resources/chromeos/login/login_shared.js

Index: chrome/browser/resources/chromeos/login/login_shared.js
diff --git a/chrome/browser/resources/chromeos/login/login_shared.js b/chrome/browser/resources/chromeos/login/login_shared.js
index 160da795f67822e8353ca0f0d9de9683e5676fae..314c671eb3a639b26024e92e530807b18cae6116 100644
--- a/chrome/browser/resources/chromeos/login/login_shared.js
+++ b/chrome/browser/resources/chromeos/login/login_shared.js
@@ -441,5 +441,10 @@ disableTextSelectAndDrag(function(e) {
   document.addEventListener('DOMContentLoaded', function() {
     Oobe.initialize();
   });
+
+  // Install a global error handler so stack traces are included in logs.
+  window.onerror = function(message, file, line, column, error) {
+    console.error(error.stack);
+  }
 })();