Update TodoMVC based on https://github.com/polymer/todomvc

pkg/polymer/lib/src/build/linter.dart

Index: pkg/polymer/lib/src/build/linter.dart
diff --git a/pkg/polymer/lib/src/build/linter.dart b/pkg/polymer/lib/src/build/linter.dart
index f186d310191507ed4561d7825fb29d3b50faafa9..36c7ec3199cc93811ef8c2ac6e960d99e3ed2128 100644
--- a/pkg/polymer/lib/src/build/linter.dart
+++ b/pkg/polymer/lib/src/build/linter.dart
@@ -254,11 +254,6 @@ class _LinterVisitor extends TreeVisitor {
     if (_isEntrypoint && !_dartTagSeen) {
       _logger.error(USE_INIT_DART, span: doc.body.sourceSpan);
     }
-
-    if (_isEntrypoint && !_dartJSSeen) {
-      // TODO(sigmund): remove this when webkitStartDart is gone.
-      _logger.error(USE_DART_JS, span: doc.body.sourceSpan);
-    }
   }
 
   /** Produce warnings for invalid link-rel tags. */
@@ -496,15 +491,6 @@ class _LinterVisitor extends TreeVisitor {
           span: node.attributeSpans[name]);
     }
 
-    var eventName = name.substring('on-'.length);
-    if (eventName.contains('-')) {
-      var newEvent = toCamelCase(eventName);
-      _logger.warning('Invalid event name "$name". After the "on-" the event '
-          'name should not use dashes. For example use "on-$newEvent" or '
-          '"on-${newEvent.toLowerCase()}" (both forms are equivalent in HTML).',
-          span: node.attributeSpans[name]);
-    }
-
     if (value.contains('.') || value.contains('(')) {
       _logger.warning('Invalid event handler body "$value". Declare a method '
           'in your custom element "void handlerName(event, detail, target)" '
@@ -548,10 +534,6 @@ const String USE_INIT_DART =
     '</script>\' or add your own script tag and call that function. '
     'Make sure the script tag is placed after all HTML imports.';
 
-const String USE_DART_JS =
-    'To run a polymer applications in Dartium, make sure to include'
-    '\'<script src="packages/browser/dart.js"></script>\' in your page';
-
 const String BOOT_JS_DEPRECATED =
     '"boot.js" is now deprecated. Instead, you can initialize your polymer '
     'application by calling "initPolymer()" in your main. If you don\'t have a '