Allow resource loads inside page unload events

Allow resource loads inside page unload events

https://src.chromium.org/viewvc/blink?revision=154852&view=revision appears
to have inadvertently caused ResourceFetcher::shouldLoadNewResource() to return
false inside of unload events. This is because activeDocumentLoader() has
switched to the provisional document loader, but the request is coming from
the committed document loader.

Test written by sigbjornf@opera.com

BUG=321241
TEST=http/tests/xmlhttprequest/xmlhttprequest-unload-sync.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=163151

[abarth-chromium, 2013-12-04 05:58:48]

lgtm

Oh well.  It would have been nice to not need to support this case.

[commit-bot: I haz the power, 2013-12-04 05:58:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/japhet@chromium.org/102353004/1

[sof, 2013-12-04 06:20:27]

Looks fine, tidier way to express it.

(That sync XHR is used here is perhaps an indication that other mechanisms for
saving state on unload aren't considered sufficient. Something to look into.)

[commit-bot: I haz the power, 2013-12-04 09:45:30]

Change committed as 163151

[sof, 2014-01-28 15:57:40]

On 2013/12/04 05:58:48, abarth wrote:
> lgtm
> 
> Oh well.  It would have been nice to not need to support this case.

Beacon might help us here,
https://dvcs.w3.org/hg/webperf/raw-file/tip/specs/Beacon/Overview.html