Fix triple slash comments new paragraph spacing.

pkg/docgen/lib/docgen.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.
 
 /// **docgen** is a tool for creating machine readable representations of Dart
 /// code metadata, including: classes, members, comments and annotations.
 ///
 /// docgen is run on a `.dart` file or a directory containing `.dart` files.
 ///
 ///      $ dart docgen.dart [OPTIONS] [FILE/DIR]
@@ skipping 325 matching lines @@
       'libraries' : filteredEntities.where((e) =>
           e is Library).map((e) => e.previewMap).toList(),
       'introduction' : introduction == '' ?
           '' : markdown.markdownToHtml(new File(introduction)
               .readAsStringSync(), linkResolver: linkResolver,
                   inlineSyntaxes: markdownSyntaxes),
       'filetype' : outputToYaml ? 'yaml' : 'json'
     };
   }
   _writeToFile(JSON.encode(libraryMap), 'library_list.json');
+
   // Output libraries and classes to file after all information is generated.
   filteredEntities.where((e) => e is Class || e is Library).forEach((output) {
     _writeIndexableToFile(output, outputToYaml);
   });
+
   // Outputs all the qualified names documented with their type.
   // This will help generate search results.
   _writeToFile(filteredEntities.map((e) =>
       '${e.qualifiedName} ${e.typeName}').join('\n') + '\n',
       'index.txt', append: append);
   var index = new Map.fromIterables(
       filteredEntities.map((e) => e.qualifiedName),
       filteredEntities.map((e) => e.typeName));
   if (append) {
     var previousIndex =
@@ skipping 83 matching lines @@
 /// simple markdown converted to html.
 String _commentToHtml(DeclarationMirror mirror) {
   String commentText;
   mirror.metadata.forEach((metadata) {
     if (metadata is CommentInstanceMirror) {
       CommentInstanceMirror comment = metadata;
       if (comment.isDocComment) {
         if (commentText == null) {
           commentText = comment.trimmedText;
         } else {
-          commentText = '$commentText ${comment.trimmedText}';
+          commentText = '$commentText\n${comment.trimmedText}';
         }
       }
     }
   });
 
   commentText = commentText == null ? '' :
       markdown.markdownToHtml(commentText.trim(), linkResolver: linkResolver,
           inlineSyntaxes: markdownSyntaxes);
   return commentText;
 }
@@ skipping 772 matching lines @@
 String docName(DeclarationMirror m) {
   if (m is LibraryMirror) {
     return (m as LibraryMirror).qualifiedName.replaceAll('.','-');
   }
   var owner = m.owner;
   if (owner == null) return m.qualifiedName;
   // For the unnamed constructor we just return the class name.
   if (m.simpleName == '') return docName(owner);
   return docName(owner) + '.' + m.simpleName;
 }