Verifies that find and replace can be used to replace words in an editable area. This test requires WebKitTestRunner.

After replacing 'orange' with 'apricot':
| "\n        "
| <p>
|   "Apple banana <#selection-anchor>apricot<#selection-focus>."
| "\n        "
| <p>
|   "Kiwi banana pear."
| "\n    "

After replacing 'banana' with 'watermelon':
| "\n        "
| <p>
|   "Apple <#selection-anchor>watermelon<#selection-focus> apricot."
| "\n        "
| <p>
|   "Kiwi watermelon pear."
| "\n    "