Test tidying: use "escape" and "backspace" with eventSender.keyDown()

LayoutTests/fast/events/key-events-in-input-text.html

 <p>To test manually, press keys and compare results to other browsers.</p>
 <input type="text"
    onclick="log(eventInfo(event));"
    onmousedown="log(eventInfo(event));"
    onmouseup="log(eventInfo(event));"
    onkeypress="log(eventInfo(event));"
    onkeydown="log(eventInfo(event));"
    onkeyup="log(eventInfo(event));">
 </input>
 <input type=text></input>
@@ skipping 34 matching lines @@
 if (document.getElementsByTagName("input")[0].addEventListener)
     document.getElementsByTagName("input")[0].addEventListener('textInput', function(e) {log(eventInfo(e));}, false);
 
 document.getElementsByTagName("input")[0].focus();
 
 if (window.testRunner) {
     testRunner.dumpAsText();
     log("Space:");
     eventSender.keyDown(" ", []);
     log("Backspace:");
-    eventSender.keyDown("\x08", []);
+    eventSender.keyDown("backspace", []);
     log("Left Arrow:");
     eventSender.keyDown("leftArrow", []);
     log("Tab:");
     eventSender.keyDown("\t", []);
 }
 </script>