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

pkg/polymer/lib/src/css_emitters.dart

-// 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.css_emitters;
-
-import 'package:csslib/visitor.dart' show Visitor, CssPrinter, ElementSelector,
-       UriTerm, Selector, HostDirective, SimpleSelectorSequence, StyleSheet;
-
-import 'info.dart';
-
-
-/** Emit the contents of the style tag outside of a component. */
-String emitStyleSheet(StyleSheet ss, FileInfo file) =>
-  (new _CssEmitter(file.components.keys.toSet())
-      ..visitTree(ss, pretty: true)).toString();
-
-/** Emit a component's style tag content emulating scoped css. */
-String emitComponentStyleSheet(StyleSheet ss, String tagName) =>
-    (new _ComponentCssEmitter(tagName)..visitTree(ss, pretty: true)).toString();
-
-String emitOriginalCss(StyleSheet css) =>
-    (new CssPrinter()..visitTree(css)).toString();
-
-/** Only x-tag name element selectors are emitted as [is="x-"]. */
-class _CssEmitter extends CssPrinter {
-  final Set _componentsTag;
-  _CssEmitter(this._componentsTag);
-
-  void visitElementSelector(ElementSelector node) {
-    // If element selector is a component's tag name, then change selector to
-    // find element who's is attribute's the component's name.
-    if (_componentsTag.contains(node.name)) {
-      emit('[is="${node.name}"]');
-      return;
-    }
-    super.visitElementSelector(node);
-  }
-}
-
-/**
- * Emits a css stylesheet applying rules to emulate scoped css. The rules adjust
- * element selectors to include the component's tag name.
- */
-class _ComponentCssEmitter extends CssPrinter {
-  final String _componentTagName;
-  bool _inHostDirective = false;
-  bool _selectorStartInHostDirective = false;
-
-  _ComponentCssEmitter(this._componentTagName);
-
-  /** Is the element selector an x-tag name. */
-  bool _isSelectorElementXTag(Selector node) {
-    if (node.simpleSelectorSequences.length > 0) {
-      var selector = node.simpleSelectorSequences[0].simpleSelector;
-      return selector is ElementSelector && selector.name == _componentTagName;
-    }
-    return false;
-  }
-
-  void visitSelector(Selector node) {
-    // If the selector starts with an x-tag name don't emit it twice.
-    if (!_isSelectorElementXTag(node)) {
-      if (_inHostDirective) {
-        // Style the element that's hosting the component, therefore don't emit
-        // the descendent combinator (first space after the [is="x-..."]).
-        emit('[is="$_componentTagName"]');
-        // Signal that first simpleSelector must be checked.
-        _selectorStartInHostDirective = true;
-      } else {
-        // Emit its scoped as a descendent (space at end).
-        emit('[is="$_componentTagName"] ');
-      }
-    }
-    super.visitSelector(node);
-  }
-
-  /**
-   * If first simple selector of a ruleset in a @host directive is a wildcard
-   * then don't emit the wildcard.
-   */
-  void visitSimpleSelectorSequence(SimpleSelectorSequence node) {
-    if (_selectorStartInHostDirective) {
-      _selectorStartInHostDirective = false;
-      if (node.simpleSelector.isWildcard) {
-        // Skip the wildcard if first item in the sequence.
-        return;
-      }
-      assert(node.isCombinatorNone);
-    }
-
-    super.visitSimpleSelectorSequence(node);
-  }
-
-  void visitElementSelector(ElementSelector node) {
-    // If element selector is the component's tag name, then change selector to
-    // find element who's is attribute is the component's name.
-    if (_componentTagName == node.name) {
-      emit('[is="$_componentTagName"]');
-      return;
-    }
-    super.visitElementSelector(node);
-  }
-
-  /**
-   * If we're polyfilling scoped styles the @host directive is stripped.  Any
-   * ruleset(s) processed in an @host will fixup the first selector.  See
-   * visitSelector and visitSimpleSelectorSequence in this class, they adjust
-   * the selectors so it styles the element hosting the compopnent.
-   */
-  void visitHostDirective(HostDirective node) {
-    _inHostDirective = true;
-    emit('/* @host */');
-    for (var ruleset in node.rulesets) {
-      ruleset.visit(this);
-    }
-    _inHostDirective = false;
-    emit('/* end of @host */\n');
-  }
-}