Javascript: Meu 2o programa

Copie o programinha abaixo num bloco de notas e salve-o como 2o-js.html, por exemplo.
<style>
p.destaque b {color: #800000; padding-left: 4px; padding-right: 4px; }
p.destaque b:hover {color: #e00000; background-color: #ffffe0}
</style>
<p onDblClick= "pegaPalavra();" class="destaque">Se você acha que não sabe nada de inglês, então leia estas palavras: milkshake, hamburguer, diet, light, designer, sundown, top model, outdoor, delete, notebook, big brother, cd room, pop star, windows, word, dowloand, mensseger, mc donald's, bob's, drink, hotmail, website, hotdog, shopping, show room, play station, lan house, drive throw, fast food, pit stop, feeling, show, pen drive, rock, shampoo, free style, hip hop, street fighter, look, desktop, brother, ok, funk, stress, handball, volleyball, basketball, net, new look, paper view, champion, time, always, god, the flash, password, slow motion, picture, zoom, login, delivery, quick.</p>
<script>
function pegaPalavra () {
var palavra= window.getSelection().getRangeAt (0);
var tag_bold = document.createElement ("b");
palavra.surroundContents (tag_bold);
}
</script>
Aviso: Este programa poderá não funcionar no iExplorer.