[WebPositive] crash in WebCore::TimerBase::setNextFireTime

[diver]

Started and immediately closed Web+ a few times and it crashed.

Debug information for team /boot/system/apps/WebPositive (2102):
CPU(s): 2x Intel Core™ i7-3635QM
Memory: 1.46 GiB total, 352.84 MiB used
Haiku revision: hrev53898 Feb 21 2020 08:06:23 (x86_64)

Active Threads:
	thread 2102: WebPositive (main)
	thread 2147: team 2102 debug task 
	thread 2145: w>WebPositive 
		state: Call (abort() called)

		Frame		IP			Function Name
		-----------------------------------------------
		00000000	0x2009f7a21bf	_kern_debugger + 0x7 
			Disassembly:
				_kern_debugger:
				0x000002009f7a21b8:   48c7c0e1000000  mov $0xe1, %rax
				0x000002009f7a21bf:             0f05  syscall  <--

		0x7fdfeee1c4e0	0x2009f799c93	abort + 0x4a 
		0x7fdfeee1c530	0x3bc2603820	WebCore::TimerBase::setNextFireTime(WTF::MonotonicTime) + 0x190 
		0x7fdfeee1c560	0x3bc24785dd	WebCore::NavigationScheduler::cancel(WebCore::NewLoadInProgress) + 0x2d 
		0x7fdfeee1c580	0x3bc2468f21	WebCore::FrameLoader::closeURL() + 0x61 
		0x7fdfeee1c5c0	0x3bc24690cf	WebCore::FrameLoader::detachFromParent() + 0x1f 
		0x7fdfeee1c5e0	0x3bc1f5af7b	BWebPage::~BWebPage() + 0x3b 
		0x7fdfeee1c600	0x3bc1f5afec	BWebPage::~BWebPage() + 0xc 
		0x7fdfeee1c620	0x3bc1f62c47	BWebView::~BWebView() + 0x27 
		0x7fdfeee1c640	0x3bc1f62cec	BWebView::~BWebView() + 0xc 
		0x7fdfeee1c660	0x1441ba6c767	BView::~BView() + 0x47 
		0x7fdfeee1c680	0x1441ba6c84c	BView::~BView() + 0xc 
		0x7fdfeee1c6a0	0x1441ba6c767	BView::~BView() + 0x47 
		0x7fdfeee1c6c0	0x1441b9fa1dc	BGroupView::~BGroupView() + 0xc 
		0x7fdfeee1c6e0	0x1441ba6c767	BView::~BView() + 0x47 
		0x7fdfeee1c700	0x1441ba6c84c	BView::~BView() + 0xc 
		0x7fdfeee1c760	0x1441ba74361	BWindow::~BWindow() + 0xc1 
		0x7fdfeee1c7b0	0x436dd176bc	BrowserWindow::~BrowserWindow() + 0x9c 
		0x7fdfeee1c7d0	0x436dd176dc	BrowserWindow::~BrowserWindow() + 0xc 
		0x7fdfeee1c7f0	0x1441b9b9eec	BLooper::_task0_(void*) + 0x2c 
		0x7fdfeee1c810	0x2009f7a0f67	thread_entry + 0x17 
		00000000	0x7f6fe1623260	commpage_thread_exit + 0 

[cocobean]

diver - Tested with Haiku R1B3 (+56) x64 and Web+ 1.2-alpha/HaikuWebKit 1.8.2-2. Open and closed (Alt+Q) Web+ four times consistently without any crash. No crash.