[whatwg] Introducing new elements is expensive

[Matthew Raymond]

Anne van Kesteren wrote:
> Matthew Raymond wrote:
> 
>>By the way, is there a reason that <output> can't have a |value| 
>>attribute? What if we want the initial contents on a legacy UA to be 
>>"Calculation Not Available", or perhaps an <input type="text" readonly> 
>>element like you suggest? Is this an example of Ian trying to avoid 
>><noscript>-style elements?
> 
> From:
>   <http://whatwg.org/specs/web-forms/current-work/#the-output>
> 
> # Its current value is given by its contents, which may be any inline
> # content (like the span element).

    You completely missed the point. The idea is that the inline content 
in a legacy UA would be *intentionally* different from the |value| 
attribute as a way of providing separate content for WF2 UAs and legacy UAs:

| <output value="0" onforminput="value = a.value * b.value">
|  <input type="text" readonly="readonly" value="0">
|  <script type="text/javascript" src="onforminput.js"></script>
| </output>