Nested comments.

dart/frog/leg/scanner/scanner.dart

 // 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.
 
 interface Scanner {
   Token tokenize();
 }
 
 /**
  * Common base class for a Dart scanner.
@@ skipping 500 matching lines @@
   int tokenizeSingleLineComment(int next) {
     while (true) {
       next = advance();
       if ($LF === next || $CR === next || $EOF === next) {
         return next;
       }
     }
   }
 
   int tokenizeMultiLineComment(int next) {
+    int nesting = 1;
     next = advance();
     while (true) {
       if ($EOF === next) {
+        // TODO(ahe): Report error.
         return next;
       } else if ($STAR === next) {
         next = advance();
-        if (next === $SLASH) {
-          return advance();
-        } else if (next === $EOF) {
-          return next;
+        if ($SLASH === next) {
+          --nesting;
+          if (0 === nesting) {
+            return advance();
+          } else {
+            next = advance();
+          }
+        }
+      } else if ($SLASH === next) {
+        next = advance();
+        if ($STAR === next) {
+          next = advance();
+          ++nesting;
         }
       } else {
         next = advance();
       }
     }
   }
 
   int tokenizeKeywordOrIdentifier(int next, bool allowDollar) {
     KeywordState state = KeywordState.KEYWORD_STATE;
     int start = byteOffset;
@@ skipping 157 matching lines @@
     }
     return next;
   }
 }
 
 class MalformedInputException {
   final message;
   MalformedInputException(this.message);
   toString() => message.toString();
 }