[html5lib] triple slash comment style

tools/line_doc_comments.dart

 #!/usr/bin/env dart
 
 /// Converts block-style Doc comments in Dart code to line style.
 library line_doc_comments;
 import 'dart:io';
 
 import '../pkg/path/lib/path.dart' as path;
 
 final oneLineBlock = new RegExp(r'^(\s*)/\*\*\s?(.*)\*/\s*$');
 final startBlock = new RegExp(r'^(\s*)/\*\*(.*)$');
@@ skipping 15 matching lines @@
         if (entity is File) {
           var file = entity.path;
           if (path.extension(file) != '.dart') return;
           fixFile(file);
         }
       });
 }
 
 void fixFile(String path) {
   var file = new File(path);
-  file.readAsLines().then(fixContents).then((fixed) {
+  file.readAsLines().then((lines) => fixContents(lines, path)).then((fixed) {
     return new File(path).writeAsString(fixed);
   }).then((file) {
     print(file.path);
   });
 }
 
-String fixContents(List<String> lines) {
+String fixContents(List<String> lines, String path) {
   var buffer = new StringBuffer();
+  var linesOut = 0;
   var inBlock = false;
   var indent;
+
   for (var line in lines) {
+    var oldLine = line;
     if (inBlock) {
       // See if it's the end of the comment.
       if (endBlock.hasMatch(line)) {
         inBlock = false;
 
         // Just a pointless line, delete it!
         line = null;
       } else {
         var match = blockLine.firstMatch(line);
         var comment = match[1];
@@ skipping 27 matching lines @@
             // Got comment on /** line.
             line = match[2];
           } else {
             // Just a pointless line, delete it!
             line = null;
           }
         }
       }
     }
 
-    if (line != null) buffer.write('$line\n');
+    if (line != null) {
+      linesOut++;
+
+      // Warn about lines that crossed 80 columns as a result of the change.
+      if (line.length > 80 && oldLine.length <= 80) {
+        const _PURPLE = '\u001b[35m';
+        const _RED = '\u001b[31m';
+        const _NO_COLOR = '\u001b[0m';
+
+        print('$_PURPLE$path$_NO_COLOR:$_RED$linesOut$_NO_COLOR: '
+            'line exceeds 80 cols:\n    $line');
+      }
+
+      buffer.write('$line\n');
+    }
   }
 
   return buffer.toString();
 }