DevTools: [Regression] setting property text throws exceptions

Source/devtools/front_end/sdk/CSSStyleModel.js

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1311 matching lines @@
          * @param {!WebInspector.TokenizerFactory} tokenizerFactory
          */
         function processTokens(tokenizerFactory)
         {
             var tokenize = tokenizerFactory.createTokenizer("text/css");
             tokenize(styleText, processToken);
             callback(result + (indentation ? "\n" + endIndentation : ""));
         }
 
         var lastWasSemicolon = true;
+        var lastWasMeta = false;
         var insideProperty = false;
         /**
          * @param {string} token
          * @param {?string} tokenType
          * @param {number} column
          * @param {number} newColumn
          */
         function processToken(token, tokenType, column, newColumn)
         {
             var isSemicolon = token === ";";
@@ skipping 12 matching lines @@
                 return;
             if (tokenType === "css-comment" && token.includes(":") && token.includes(";")) {
                 result += "\n" + indentation + token;
                 insideProperty = false;
                 return;
             }
 
             if (isSemicolon)
                 insideProperty = false;
 
-            if (tokenType === "css-tag") {
+            if (tokenType === "css-meta" || (tokenType === "css-tag" && !lastWasMeta)) {
                 result += "\n" + indentation;
                 insideProperty = true;
             }
             result += token;
+
+            lastWasMeta = tokenType === "css-meta";
         }
     },
 
     /**
      * @param {string} text
      * @return {string}
      */
     _detectIndentation: function(text)
     {
         var lines = text.split("\n");
@@ skipping 620 matching lines @@
  * @constructor
  * @param {?WebInspector.CSSStyleDeclaration} inlineStyle
  * @param {?WebInspector.CSSStyleDeclaration} attributesStyle
  */
 WebInspector.CSSStyleModel.InlineStyleResult = function(inlineStyle, attributesStyle)
 {
     this.inlineStyle = inlineStyle;
     this.attributesStyle = attributesStyle;
 }