CSS Parser: Support CDO and CDC tokens (<!--, -->)

Source/core/css/parser/SizesCalcParser.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/css/parser/SizesCalcParser.h"
 
 #include "core/css/MediaValues.h"
 #include "core/css/parser/CSSParserToken.h"
 
@@ skipping 112 matching lines @@
             // If the stack runs out without finding a left parenthesis, then there are mismatched parentheses.
             if (stack.isEmpty())
                 return false;
             // Pop the left parenthesis from the stack, but not onto the output queue.
             stack.removeLast();
             break;
         case CommentToken:
         case WhitespaceToken:
         case EOFToken:
             break;
+        case CDOToken:
+        case CDCToken:
         case AtKeywordToken:
         case HashToken:
         case UrlToken:
         case BadUrlToken:
         case PercentageToken:
         case IncludeMatchToken:
         case DashMatchToken:
         case PrefixMatchToken:
         case SuffixMatchToken:
         case SubstringMatchToken:
@@ skipping 78 matching lines @@
         }
     }
     if (stack.size() == 1 && stack.last().isLength) {
         m_result = std::max(clampTo<float>(stack.last().value), (float)0.0);
         return true;
     }
     return false;
 }
 
 } // namespace blink