Plugin content crashes QWebView with MinGW 4.8

When a QWebView loads any page with plugin content, it will crash the QT application. This only affects versions of QT that use MinGW 4.8. There was an issue back in 4.6.0 and it was also a MinGW issue: https://bugreports.qt-project.org/browse/QTBUG-4932

In debug mode I get this error returned:

ASSERTION FAILED: !lookupForWriting(Extractor::extract(entry)).second
..\WTF/wtf/HashTable.h(952) : void WTF::HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits>::reinsert(WTF::HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits>::ValueType&) [with Key = WTF::RefPtr<WTF::StringImpl>; Value = WTF::KeyValuePair<WTF::RefPtr<WTF::StringImpl>, WebCore::IdentifierRep*>; Extractor = WTF::KeyValuePairKeyExtractor<WTF::KeyValuePair<WTF::RefPtr<WTF::StringImpl>, WebCore::IdentifierRep*> >; HashFunctions = WTF::StringHash; Traits = WTF::KeyValuePairHashTraits<WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >, WTF::HashTraits<WebCore::IdentifierRep*> >; KeyTraits = WTF::HashTraits<WTF::RefPtr<WTF::StringImpl> >; WTF::HashTable<Key, Value, Extractor, HashFunctions

A project and build is attached that should provide a simple example of what's going on. The debugger ends up pointing to a Flash.dll somewhere in SysWOW64 folder, which I find strange. Maybe it's looking for / finding a bad DLL?