Comment 4 for bug 412166

Browsers and the HTML 5 specification are converging on parsing behavior needed for compatibility with the Web. According to the current draft of the HTML 5 specification, Chrome is doing the right thing: <span> is a phrasing element, and is therefore not in the class of elements that is allowed to close itself.

You can see this behavior at the HTML 5 validator. <http://livedom.validator.nu/?%3C!DOCTYPE%20html%3E%0A%3Chtml%3E%3Cspan%20%2F%3EThe%20rain%20in%20Spain%20is%20%3Ci%3Emainly%3C%2Fi%3E%20in%20the%20plain.%3C%2Fhtml%3E>

So, it's a bug in Launchpad.