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

LayoutTests/fast/forms/resources/textarea-live-pseudo-selectors.js

 description("This test performs a check that :valid/:invalid CSS psudo selectors are lively applied.");
 
 // Setup for static elements.
 var form = document.createElement('form');
 document.body.appendChild(form);
 var nonForm = document.createElement('div');
 document.body.appendChild(nonForm);
 
 function makeInvalid() {
     var i = document.createElement('textarea');
@@ skipping 58 matching lines @@
 el.value = 'abc';
 shouldBe(elBackground, 'validColor');
 el.value = '';
 shouldBe(elBackground, 'invalidColor');
 
 debug('Change the value by key input:');
 el = makeInvalid();
 el.focus();
 eventSender.keyDown('a');
 shouldBe(elBackground, 'validColor');
-eventSender.keyDown('\x08', []);
+eventSender.keyDown('backspace', []);
 shouldBe(elBackground, 'invalidColor');
 
 // --------------------------------
 //     Constraints change
 // --------------------------------
 debug('Change required:');
 el = makeInvalid();
 el.required = false;
 shouldBe(elBackground, 'validColor');
 el.required = true;
 shouldBe(elBackground, 'invalidColor');
 
 debug('Change maxlength:');
 el = makeInvalid();
 el.value = '1234567890';
 shouldBe(elBackground, 'validColor');
 // Make the value dirty by deleting the last character.
 el.focus();
 el.setSelectionRange(10, 10);
 document.execCommand('delete');
 el.maxLength = 5;
 shouldBe(elBackground, 'invalidColor');
 el.maxLength = 10;
 shouldBe(elBackground, 'validColor');