Revert of DevTools: NetworkPanel: Preview: do not try to show HTML as JSONP.

Revert of DevTools: NetworkPanel: Preview: do not try to show HTML as JSONP. (patchset #1 id:1 of https://codereview.chromium.org/973813003/)

Reason for revert:
See https://code.google.com/p/chromium/issues/detail?id=492540

Original issue's description:
> DevTools: NetworkPanel: Preview: do not try to show HTML as JSONP.
> 
> BUG=
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=191295

TBR=eustas@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=195965

[pfeldman, 2015-05-27 09:18:53]

Created Revert of DevTools: NetworkPanel: Preview: do not try to show HTML as
JSONP.

[commit-bot: I haz the power, 2015-05-27 09:19:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1148133004/1

[commit-bot: I haz the power, 2015-05-27 09:19:58]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=195965

[eustas, 2015-05-27 12:24:45]

On 2015/05/27 09:19:58, I haz the power - commit-bot wrote:
> Committed patchset #1 (id:1) as
> https://src.chromium.org/viewvc/blink?view=rev&revision=195965

I'm quite sure that this revert is wrong.
The original CL touches only XHR and only if their mime type is HTML.
Developers asked to see what error was send by server.

In bug you've tried to fix the description of what is wrong it very common. And
most probably it is error on developers server (setting wrong mime).

BUG: https://code.google.com/p/chromium/issues/detail?id=492540

[pfeldman, 2015-05-27 12:32:55]

> I'm quite sure that this revert is wrong.
> The original CL touches only XHR and only if their mime type is HTML.
> Developers asked to see what error was send by server.

I did not find the bug it was fixing.

> In bug you've tried to fix the description of what is wrong it very common.
And
> most probably it is error on developers server (setting wrong mime).

There is no such thing as wrong mime type when we are talking about json (yes,
in this case it is text/html), we should infer JSON-ability via parsing. Your
check for being HTML via parsing will give false positives for any JSON content.

> BUG: https://code.google.com/p/chromium/issues/detail?id=492540

[eustas, 2015-05-27 13:10:15]

On 2015/05/27 12:32:55, pfeldman wrote:
> > I'm quite sure that this revert is wrong.
> > The original CL touches only XHR and only if their mime type is HTML.
> > Developers asked to see what error was send by server.
> 
> I did not find the bug it was fixing.
> 
> > In bug you've tried to fix the description of what is wrong it very common.
> And
> > most probably it is error on developers server (setting wrong mime).
> 
> There is no such thing as wrong mime type when we are talking about json (yes,
> in this case it is text/html), we should infer JSON-ability via parsing. Your
> check for being HTML via parsing will give false positives for any JSON
content.
> 
> > BUG: https://code.google.com/p/chromium/issues/detail?id=492540

Actually, XHR isn't always JSON. It may be XML, HTML, anything.
Agree - we should check by parsing.

But in the case of mime type == text/html almost any content is valid, as it
could be rendered as a page.