First pass at a markdown parser in Dart.

utils/markdown/html_renderer.dart

Index: utils/markdown/html_renderer.dart
diff --git a/utils/markdown/html_renderer.dart b/utils/markdown/html_renderer.dart
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+// Copyright (c) 2011, 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.
+
+String renderToHtml(List<Node> nodes) => new HtmlRenderer().render(nodes);
+
+/// Translates a parsed AST to HTML.
+class HtmlRenderer implements NodeVisitor {
+  static final _BLOCK_TAGS = const RegExp(
+      'blockquote|h1|h2|h3|h4|h5|h6|hr|p|pre');
+
+  StringBuffer buffer;
+
+  HtmlRenderer();
+
+  String render(List<Node> nodes) {
+    buffer = new StringBuffer();
+
+    for (final node in nodes) node.accept(this);
+
+    return buffer.toString();
+  }
+
+  void visitText(Text text) {
+    buffer.add(text.text);
+  }
+
+  bool visitElementBefore(Element element) {
+    // Hackish. Separate block-level elements with newlines.
+    if (!buffer.isEmpty() &&
+        _BLOCK_TAGS.firstMatch(element.tag) != null) {
+      buffer.add('\n');
+    }
+
+    buffer.add('<${element.tag}');
+
+    for (final name in element.attributes.getKeys()) {
+      buffer.add(' $name="${element.attributes[name]}"');
+    }
+
+    if (element.isEmpty) {
+      // Empty element like <hr/>.
+      buffer.add(' />');
+      return false;
+    } else {
+      buffer.add('>');
+      return true;
+    }
+  }
+
+  void visitElementAfter(Element element) {
+    buffer.add('</${element.tag}>');
+  }
+}