Bug 242262

Crash under ~TimerBase() from LibWebRTCAudioModule:

Thread 17 Crashed::   Dispatch queue: WebKitWebRTCAudioModule
0   WebCore                       	       0x18fd8cc44 WTFCrashWithInfo(int, char const*, char const*, int) + 20 (wtf/Assertions.h:697)
1   WebCore                       	       0x1918dbcb4 WebCore::TimerBase::~TimerBase() + 272 (Source/WebCore/./platform/Timer.cpp:262)
2   WebCore                       	       0x191a983ec rtc::RefCountedObject<WebCore::LibWebRTCAudioModule>::~RefCountedObject() + 136 (Source/WebCore/platform/Timer.h:108)
3   WebCore                       	       0x191a98260 rtc::RefCountedObject<WebCore::LibWebRTCAudioModule>::Release() const + 76 (webrtc/rtc_base/ref_counted_object.h:42)
4   WebCore                       	       0x18feb630c WTF::Detail::CallableWrapper<WebCore::LibWebRTCAudioModule::pollAudioData()::$_4, void>::~CallableWrapper() + 92 (webrtc/api/scoped_refptr.h:102)
5   JavaScriptCore                	       0x18ce0c450 void WTF::dispatchWorkItem<WTF::(anonymous namespace)::DispatchWorkItem>(void*) + 108 (/usr/include/c++/v1/memory:1428)
6   libdispatch.dylib             	       0x18061f518 _dispatch_client_callout + 20
7   libdispatch.dylib             	       0x180622a48 _dispatch_continuation_pop + 504
8   libdispatch.dylib             	       0x180635c7c _dispatch_source_invoke + 1364
9   libdispatch.dylib             	       0x180626c80 _dispatch_lane_serial_drain + 372
10  libdispatch.dylib             	       0x180627920 _dispatch_lane_invoke + 408
11  libdispatch.dylib             	       0x1806321b4 _dispatch_workloop_worker_thread + 660
12  libsystem_pthread.dylib       	       0x1f0b40064 _pthread_wqthread + 288
13  libsystem_pthread.dylib       	       0x1f0b3fdfc start_wqthread + 8