ego confused by 'bulletproof button'

It's a common pattern in email templates to use 'bulletproof buttons'
https://www.litmus.com/blog/a-guide-to-bulletproof-buttons-in-email-design/

but this confuses ego, e.g. this snippet of HTML in an ego template
```html

```
causes ego to emit

```go
//line email_gift_fulfilled_html.ego:33
_, _ = io.WriteString(w, html.EscapeString(fmt.Sprint(lib.FormatMoney(enrollment.Plan.GiftValue, 0, 2, false, true))))
//line email_gift_fulfilled_html.ego:33
_, _ = io.WriteString(w, " gift. It's now ready and \n you can pick it up here:\n

\n \n \n \n

Reproduce the failure with the bulletproof-button template shown in the issue, then inspect the generated Go around the v.roundrect and v.fill blocks. Trace how the template parser handles namespaced HTML or VML tags; done means the template compiles without undefined v errors and preserves the conditional button markup.

Written by the indexing model from the issue text.