Timeout error when closing the browser before the page

[inancgumus]

Discovered by grafana/xk6-browser#141.

For this test:

func TestPageGoto(t *testing.T) {
	t.Parallel()

	b := testBrowser(t, withFileServer())

	p := b.NewPage(nil)

	url := b.staticURL("empty.html")
	r := p.Goto(url, nil)

	assert.Equal(t, url, r.URL(), `expected URL to be %q, result of navigation was %q`, url, r.URL())
}

This error may happen sometimes:

--- FAIL: TestPageGoto (30.93s)
panic: timed out [recovered]
        panic: timed out

1: running [Created by testing.(*T).Run @ testing.go:1306]
    testing  testing.go:1209             tRunner.func1.2(*T(#1), func(#4))
    testing  testing.go:1212             tRunner.func1()
             panic.go:1047               panic(interface{}{#1, grafana/xk6-browser#4})
    common   util.go:36                  Throw(...)
    common   frame_manager.go:444        (*FrameManager).NavigateFrame(*FrameManager(0xc001a66000), *Frame(#2), string(#3, len=40), Value{0x0, 0x0})
    common   frame.go:721                (*Frame).Goto(*Frame(#2), string(#3, len=40), Value{0x0, 0x0})
    common   page.go:462                 (*Page).Goto(*Page(0xc001828900), string(#3, len=40), Value{0x0, 0x0})
    tests    page_test.go:41             TestPageGoto(*T(0x0))
    testing  testing.go:1259             tRunner(*T(0xc000b53a00), func(0x2408388))
1: chan receive
    testing  testing.go:1225             tRunner.func1()
    testing  testing.go:1265             tRunner(*T(#96), func(#98))
    testing  testing.go:1596             runTests(func(#97), []InternalTest(0x1f len=31 cap=0), Time{#16, grafana/xk6-browser#12, <nil>})
    testing  testing.go:1504             (*M).Run(*M(#97))
    main     :103                        main()
1: chan receive [Created by common.(*Browser).initEvents.func1 @ browser.go:169]
    common   event_emitter.go:153        (*BaseEventEmitter).sync(*BaseEventEmitter(#598), func(#597))
    common   event_emitter.go:178        (*BaseEventEmitter).emit(*BaseEventEmitter(#598), string(#7, len=5), interface{}{#6, grafana/xk6-browser#598})
    common   page.go:155                 (*Page).didClose(*Page(#598))
    common   browser.go:282              (*Browser).onDetachedFromTarget(*Browser(#576), *EventDetachedFromTarget(#639))
27: select [Created by common.NewConnection @ connection.go:147]
    common   connection.go:216           (*Connection).handleIOError(*, {#8, grafana/xk6-browser#10})
    common   connection.go:258           (*Connection).recvLoop(*)
61: select [Created by common.(*NetworkManager).initEvents @ network_manager.go:255]
    common   network_manager.go:262      (*NetworkManager).handleEvents(*, *)
    common   network_manager.go:256      (*NetworkManager).initEvents.func1()
1: runnable [Created by chromium.(*Allocator).Allocate @ allocator.go:229]
    syscall  sys_darwin.go:44            syscall6(uintptr(#5), uintptr(#604), uintptr(#479), uintptr(0x0))
    syscall  zsyscall_darwin_amd64.go:44 wait4(824634151424, *_C_int(#604), 0, *Rusage(#479))
    syscall  syscall_bsd.go:145          Wait4(2, *WaitStatus(#605), 824661208836, *Rusage(0x2))
    os       exec_unix.go:44             (*Process).wait(*Process(#601))
    os       exec.go:132                 (*Process).Wait(...)
    exec     exec.go:507                 (*Cmd).Wait(*Cmd(#415))
    chromium allocator.go:230            (*Allocator).Allocate.func2()
396: select [Created by common.NewBaseEventEmitter @ event_emitter.go:120]
    common   event_emitter.go:130        (*BaseEventEmitter).syncAll(*, {#9, *})
1: runnable [Created by common.NewBaseEventEmitter @ event_emitter.go:120]
    common   event_emitter.go:136        (*BaseEventEmitter).syncAll(*BaseEventEmitter(#548), Context{#9, grafana/xk6-browser#577})
27: select [Created by common.(*Browser).initEvents @ browser.go:158]
    common   browser.go:160              (*Browser).initEvents.func1()
27: select [Created by common.NewConnection @ connection.go:148]
    common   connection.go:409           (*Connection).sendLoop(*)
61: select [Created by common.(*FrameSession).initEvents @ frame_session.go:206]
    common   frame_session.go:213        (*FrameSession).initEvents.func1()
39: select [Created by common.NewSession @ session.go:70]
    common   session.go:98               (*Session).readLoop(*)
27: chan receive [Created by common.NewBrowserProcess @ browser_process.go:63]
    common   browser_process.go:66       NewBrowserProcess.func1()

It looks like Page gets stuck if we close the Browser before.