[Debugger] crashes in BSplitLayout::DerivedLayoutItems ()

[diver]

This is hrev43203, gcc2hybrid.

While trying to reproduce #8091 I got another crash.

Thread 1270 caused an exception: Segment violation
[...]
[Switching to team /boot/home/Desktop/Debugger.dist (893) thread w>/boot/system/apps/StyledEdit  (1270)]
0x005a756d in BSplitLayout::DerivedLayoutItems () from /boot/system/lib/libbe.so
(gdb) bt
#0  0x005a756d in BSplitLayout::DerivedLayoutItems () from /boot/system/lib/libbe.so
#1  0x00562840 in BLayout::_LayoutWithinContext () from /boot/system/lib/libbe.so
#2  0x005d3bf1 in BView::DoLayout () from /boot/system/lib/libbe.so
#3  0x005d3ef8 in BView::_Layout () from /boot/system/lib/libbe.so
#4  0x005d3f52 in BView::_Layout () from /boot/system/lib/libbe.so
#5  0x005d3ad6 in BView::Layout () from /boot/system/lib/libbe.so
#6  0x005dd937 in BWindow::Layout () from /boot/system/lib/libbe.so
#7  0x005dac72 in BWindow::DispatchMessage () from /boot/system/lib/libbe.so
#8  0x00304d16 in TeamWindow::DispatchMessage ()
#9  0x005df084 in BWindow::task_looper () from /boot/system/lib/libbe.so
#10 0x0050a3f7 in BLooper::_task0_ () from /boot/system/lib/libbe.so
#11 0x0091495f in thread_entry () from /boot/system/lib/libroot.so
#12 0x7823bfec in ?? ()
(gdb)

[anevilyak]

Duplicate of #8091. Should have a fix ready later today.