I saw this linked to from the WHATWG mailing list with the comment: "That page works well with Opera and Firefox, and degrades gracefully in Safari 2 and Internet Explorer. It is not working well in recent WebKit nightlies, but I'm sure that is temporary." And sure enough the bubbles seem to have floated to the top of the page :)
I think this is that <svg> doesn't properly handle float:left. I expect it's being passed in values for tx, ty when drawing and then ignoring them. Not sure.
Created attachment 12440 [details] test case
Created attachment 12441 [details] Test case that illustrates float problem as well as margin, border and padding issues.
Created attachment 12442 [details] the fix (and test case)
Comment on attachment 12442 [details] the fix (and test case) Typo: + // This should only be exist for <svg> renderers there's a stray "be". r=me