pkg/string_scanner: code format, expanded dependency constraint on unittest

lib/src/string_scanner.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library string_scanner.string_scanner;
 
 import 'package:source_span/source_span.dart';
 
 import 'exception.dart';
 import 'utils.dart';
@@ skipping 89 matching lines @@
   /// instead.
   void expect(Pattern pattern, {String name}) {
     if (scan(pattern)) return;
 
     if (name == null) {
       if (pattern is RegExp) {
         var source = pattern.pattern;
         if (!_slashAutoEscape) source = source.replaceAll("/", "\\/");
         name = "/$source/";
       } else {
-        name = pattern.toString()
-            .replaceAll("\\", "\\\\").replaceAll('"', '\\"');
+        name =
+            pattern.toString().replaceAll("\\", "\\\\").replaceAll('"', '\\"');
         name = '"$name"';
       }
     }
     _fail(name);
   }
 
   /// If the string has not been fully consumed, this throws a
   /// [FormatException].
   void expectDone() {
     if (isDone) return;
@@ skipping 45 matching lines @@
     throw new StringScannerException(message, span, string);
   }
 
   // TODO(nweiz): Make this handle long lines more gracefully.
   /// Throws a [FormatException] describing that [name] is expected at the
   /// current position in the string.
   void _fail(String name) {
     error("expected $name.", position: this.position, length: 0);
   }
 }