Handle (numeric) indexed access of DOMStringMap.

Source/core/dom/DatasetDOMStringMap.cpp

 /*
  * Copyright (C) 2010 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 65 matching lines @@
     if (!attributeName.startsWith("data-"))
         return false;
 
     unsigned propertyLength = propertyName.length();
     unsigned attributeLength = attributeName.length();
 
     unsigned a = 5;
     unsigned p = 0;
     bool wordBoundary = false;
     while (a < attributeLength && p < propertyLength) {
-        if (attributeName[a] == '-' && a + 1 < attributeLength && attributeName[a + 1] != '-')
+        if (attributeName[a] == '-' && a + 1 < attributeLength && isASCIILower(attributeName[a + 1]))
             wordBoundary = true;
         else {
             if ((wordBoundary ? toASCIIUpper(attributeName[a]) : attributeName[a]) != propertyName[p])
                 return false;
             p++;
             wordBoundary = false;
         }
         a++;
     }
 
@@ skipping 95 matching lines @@
 {
     if (!isValidPropertyName(name)) {
         es.throwDOMException(SyntaxError, ExceptionMessages::failedToDelete(name, "DOMStringMap", "'" + name + "' is not a valid property name."));
         return;
     }
 
     m_element->removeAttribute(convertPropertyNameToAttributeName(name));
 }
 
 } // namespace WebCore