remove event handler warning for auto-binding template elements

pkg/polymer/lib/src/build/linter.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.
 
 /// Logic to validate that developers are correctly using Polymer constructs.
 /// This is mainly used to produce warnings for feedback in the editor.
 library polymer.src.build.linter;
 
 import 'dart:async';
 import 'dart:convert';
@@ skipping 151 matching lines @@
 
   _ElementSummary(this.tagName, this.extendsTag, this.span);
 
   String toString() => "($tagName <: $extendsTag)";
 }
 
 class _LinterVisitor extends TreeVisitor {
   BuildLogger _logger;
   AssetId _sourceId;
   bool _inPolymerElement = false;
+  bool _inAutoBindingElement = false;
   bool _dartTagSeen = false;
   bool _polymerHtmlSeen = false;
   bool _polymerExperimentalHtmlSeen = false;
   bool _isEntryPoint;
   Map<String, _ElementSummary> _elements;
 
   _LinterVisitor(
       this._sourceId, this._logger, this._elements, this._isEntryPoint) {
     // We normalize the map, so each element has a direct reference to any
     // element it extends from.
     for (var tag in _elements.values) {
       var extendsTag = tag.extendsTag;
       if (extendsTag == null) continue;
       tag.extendsType = _elements[extendsTag];
     }
   }
 
   void visitElement(Element node) {
     switch (node.localName) {
       case 'link': _validateLinkElement(node); break;
       case 'element': _validateElementElement(node); break;
       case 'polymer-element': _validatePolymerElement(node); break;
       case 'script': _validateScriptElement(node); break;
+      case 'template':
+        var isTag = node.attributes['is'];
+        if (isTag != null && AUTO_BINDING_ELEMENTS.contains(isTag)) {
+          _inAutoBindingElement = true;
+        }
+        _validateNormalElement(node);
+        super.visitElement(node);
+        _inAutoBindingElement = false;
+        break;
       default:
-         _validateNormalElement(node);
-         super.visitElement(node);
-         break;
+        _validateNormalElement(node);
+        super.visitElement(node);
+        break;
     }
   }
 
   void run(Document doc) {
     visit(doc);
 
     if (_isEntryPoint && !_dartTagSeen && !_polymerExperimentalHtmlSeen) {
       _logger.warning(MISSING_INIT_POLYMER, span: doc.body.sourceSpan);
     }
   }
@@ skipping 193 matching lines @@
             {'name': name, 'alternative': alternative}), span: span);
       return false;
     }
     return true;
   }
 
   /// Validate event handlers are used correctly.
   void _validateEventHandler(Element node, String name, String value) {
     if (!name.startsWith('on-')) return;
 
-    if (!_inPolymerElement) {
+    if (!_inPolymerElement && !_inAutoBindingElement) {
       _logger.warning(EVENT_HANDLERS_ONLY_WITHIN_POLYMER,
           span: node.attributeSpans[name]);
       return;
     }
 
 
     // Valid bindings have {{ }}, don't look like method calls foo(bar), and are
     // non empty.
     if (!value.startsWith("{{") || !value.endsWith("}}") || value.contains('(')
         || value.substring(2, value.length - 2).trim() == '') {
@@ skipping 13 matching lines @@
   } else if (segments.length > 2) {
     // web/a/foo.html => ../packages/
     upDirCount = segments.length - 2;
   }
   var reachOutPrefix = '../' * upDirCount;
   return USE_POLYMER_HTML.create({'reachOutPrefix': reachOutPrefix});
 }
 
 const List<String> INTERNALLY_DEFINED_ELEMENTS = 
     const ['auto-binding-dart', 'polymer-element'];
+const List<String> AUTO_BINDING_ELEMENTS =
+    const ['auto-binding-dart', 'auto-binding'];