Handle odd data lengths in UTF-16 decoder

LayoutTests/fast/encoding/resources/char-decoding-utils.js

-function hex(number)
-{
-    var hexDigit = "0123456789ABCDEF";
-    var hex = hexDigit.substr(number & 0xf, 1);
-    while (number > 15) {
-        number >>= 4;
-        hex = hexDigit.substr(number & 15, 1) + hex;
-    }
-    return hex;
-}
-
 function decodeText(charsetName, characterSequence)
 {
     var req = new XMLHttpRequest;
     req.open('GET', 'data:text/plain,' + characterSequence, false);
     req.overrideMimeType('text/plain; charset="' + charsetName + '"');
     req.send('');
     return req.responseText;
 }
 
 function decode(charsetName, characterSequence)
 {
     var decodedText = decodeText(charsetName, characterSequence);
     var result = "";
     for (var i = 0; i < decodedText.length; ++i) {
-        var code = hex(decodedText.charCodeAt(i));
+        var code = decodedText.charCodeAt(i).toString(16).toUpperCase();
         if (i)
             result += "/";
-        result += "U+" + ("0000" + code).substr(code.length, 4);
+        result += "U+" + ("0000" + code).slice(-4);
     }
     return result;
 }
 
 function testDecode(charsetName, characterSequence, unicode)
 {
     shouldBe("decode('" + charsetName + "', '" + characterSequence + "')", "'" + unicode + "'");
 }
 
 function batchTestDecode(inputData)
 {
     for (var i in inputData.encodings) {
         for (var j in inputData.encoded)
             testDecode(inputData.encodings[i], inputData.encoded[j], inputData.unicode[j]);
     }
 }
-