return (Compare(Substring(aString, aString+aSubstrLen), Substring(aSubstr, aSubstr+aSubstrLen), nsCaseInsensitiveStringComparator()) == 0);
return (Substring(aString, aString+aSubstrLen).Equals(Substring(aSubstr, aSubstr+aSubstrLen), nsCaseInsensitiveStringComparator()));
static PRBool CommonPrefix(const PRUnichar *aString, const PRUnichar *aSubstr, PRInt32 aSubstrLen){  if (!aSubstrLen || (nsCRT::strlen(aString) < NS_STATIC_CAST(PRUint32, aSubstrLen)))    return PR_FALSE;  return (Compare(Substring(aString, aString+aSubstrLen),                  Substring(aSubstr, aSubstr+aSubstrLen),                  nsCaseInsensitiveStringComparator()) == 0);}