Switch polymer's build.dart to use the new linter. This CL does the following

pkg/polymer/lib/src/utils_observe.dart

Index: pkg/polymer/lib/src/utils_observe.dart
diff --git a/pkg/polymer/lib/src/utils_observe.dart b/pkg/polymer/lib/src/utils_observe.dart
deleted file mode 100644
index b568d0c37e0fc6e120671e65959cf4eeaf40e74e..0000000000000000000000000000000000000000
--- a/pkg/polymer/lib/src/utils_observe.dart
+++ /dev/null
@@ -1,33 +0,0 @@
-// Copyright (c) 2013, 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 polymer.src.utils_observe;
-
-/**
- * Converts a string name with hyphens into an identifier, by removing hyphens
- * and capitalizing the following letter. Optionally [startUppercase] to
- * captialize the first letter.
- */
-String toCamelCase(String hyphenedName, {bool startUppercase: false}) {
-  var segments = hyphenedName.split('-');
-  int start = startUppercase ? 0 : 1;
-  for (int i = start; i < segments.length; i++) {
-    var segment = segments[i];
-    if (segment.length > 0) {
-      // Character between 'a'..'z' mapped to 'A'..'Z'
-      segments[i] = '${segment[0].toUpperCase()}${segment.substring(1)}';
-    }
-  }
-  return segments.join('');
-}
-
-String toHyphenedName(String word) {
-  var sb = new StringBuffer();
-  for (int i = 0; i < word.length; i++) {
-    var lower = word[i].toLowerCase();
-    if (word[i] != lower && i > 0) sb.write('-');
-    sb.write(lower);
-  }
-  return sb.toString();
-}