make the drive output prettier (#4260)

packages/flutter_driver/lib/src/error.dart

@@ -57,8 +57,10 @@ class LogRecord {
   final String loggerName;
   final String message;
 
+  String get levelDescription => level.toString().split(".").last;
+
   @override
-  String toString() => '[${"$level".split(".").last}] $loggerName: $message';
+  String toString() => '[${levelDescription.padRight(5)}] $loggerName: $message';
 }
 
 /// Package-private; users should use other public logging libraries.

packages/flutter_tools/lib/src/commands/drive.dart

@@ -321,7 +321,8 @@ void restoreTestRunner() {
 
 Future<int> runTests(List<String> testArgs) async {
   printTrace('Running driver tests.');
-  await executable.main(testArgs);
+  List<String> args = testArgs.toList()..add('-rexpanded');
+  await executable.main(args);
   return io.exitCode;
 }