It's nearly impossible to tell with certainty, because UiBinder generates code that you could have written by hand, but if you see large chunks of HTML in the script then there are good chances they come from an HTMLPanel in a UiBinder template or a UiRenderer; particularly if the string ends with <span id=' or starts with '></span> (but it could also simply come from a SafeHtmlTemplates or a hand-coded HTMLPanel or setInnerHTML call.
