Chrome Version: 59.0.3063.4
OS: Linux

What steps will reproduce the problem?
(1) Build with dcheck_always_on=true
(2) Load http://ynet.co.il

This issue is quite hard to reproduce since it is timing dependent. We have a pretty good reproduction rate (1 of 5) in our own product but I have not been able to reproduce it in content_shell or chrome.

What is the expected result?
No DCHECK triggered

What happens instead?
DCHECK is triggered with as follows:

[1:1:0425/085701.336136:9675643037286:FATAL:PendingScript.cpp(230)] Check failed: resource()->isLoaded(). 
#0 0x7fb928ed84f7 base::debug::StackTrace::StackTrace()
#1 0x7fb928ef80f7 logging::LogMessage::~LogMessage()
#2 0x7fb92b367e4c blink::PendingScript::getSource()
#3 0x7fb92b398a30 blink::ScriptLoader::execute()
#4 0x7fb92b399c4c blink::ScriptRunner::executeTaskFromQueue()
#5 0x7fb92b399c8b blink::ScriptRunner::executeTask()
#6 0x7fb928ed9a78 base::debug::TaskAnnotator::RunTask()
#7 0x7fb92a7d1a3a blink::scheduler::TaskQueueManager::ProcessTaskFromWorkQueue()
#8 0x7fb92a7d2d0d blink::scheduler::TaskQueueManager::DoWork()
#9 0x7fb928ed9a78 base::debug::TaskAnnotator::RunTask()
#10 0x7fb928f07200 base::MessageLoop::RunTask()
#11 0x7fb928f0917d base::MessageLoop::DeferOrRunPendingTask()
#12 0x7fb928f0a09e base::MessageLoop::DoWork()
#13 0x7fb928f0bcb2 base::MessagePumpDefault::Run()
#14 0x7fb928f0b43f base::MessageLoop::RunHandler()
#15 0x7fb928f31a6b base::RunLoop::Run()
#16 0x7fb92ca6a316 content::RendererMain()
#17 0x7fb928963222 content::RunZygote()
#18 0x7fb92896361b content::RunNamedProcessTypeMain()
#19 0x7fb9289636bd content::ContentMainRunnerImpl::Run()

I have debugged this down to the following scenario:
A script is loaded and is scheduled for execution. Before it is actually run there is another request for it and a revalidation is started (probably due to server http headers). Before the revalidation finishes the execution starts and the DCHECK is fired since the resource is not in "loaded" state anymore.