[Qt] ASSERTION FAILED in ResourceHandle::setDefersLoading causes crash

https://bugs.webkit.org/show_bug.cgi?id=62808

Source/WebCore:

The assertion in ResourceHandle::setDefersLoading assumes asynchronous
content delivery -- To resume a page, first, its main resource loader
calls setDefersLoading to resume loading the main content; then all the
sub-resource loaders calls setDefersLoading to resume sub-contents.
However, since QNetworkReplyHandler delivers content synchronously,
some new sub-resource loaders get created as soon as the main resource
loader resumed, and all these new sub-resource loaders set their
defersLoading flag to false. Then, the assertion fails for these new
sub-resource loaders when calling setDefersLoading on them. As a fix,
this path makes QNetworkReplyHandler deliver content asynchronously
when its load type is set to SynchronousLoad.

Reviewed by Benjamin Poulain.

Test: loader/load-defer-resume-crash.html

* platform/network/qt/QNetworkReplyHandler.cpp:
(WebCore::QNetworkReplyHandlerCallQueue::setDeferSignals):
* platform/network/qt/QNetworkReplyHandler.h:
(WebCore::QNetworkReplyHandler::setLoadingDeferred):

LayoutTests:

Added a test for the crash occurs when load deferring is turned off.

Reviewed by Benjamin Poulain.

* loader/load-defer-resume-crash-expected.txt: Added.
* loader/load-defer-resume-crash.html: Added.
* loader/resources/images.html: Added.
* platform/chromium/test_expectations.txt: Skip this test since the LayoutTestController::setDefersLoading is not implemented for chromium.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@91189 268f45cc-cd09-0410-ab3c-d52691b4dbfc