if (len == 0) return PR_FALSE;  return (Compare(nsDependentString(aString, len), nsDependentString(aSubstr, len),
return (Compare(nsDependentString(aString, aSubstrLen), nsDependentString(aSubstr, aSubstrLen),
static PRBool CommonPrefix(const PRUnichar *aString, const PRUnichar *aSubstr, PRInt32 aSubstrLen) {  PRUint32 len = MinInt(aSubstrLen, nsCRT::strlen(aString));  if (len == 0) return PR_FALSE;  return (Compare(nsDependentString(aString, len),                  nsDependentString(aSubstr, len),                  nsCaseInsensitiveStringComparator()) == 0);}