Chrome Version: 57.0.2977.0 (64-bit)
OS: Linux

What steps will reproduce the problem?
(0) Build ToT debug Chrome on Linux: master@{#442296}
(1) Navigate to https://rbyers.github.io/paint.html
(2) Perform a multi-finger-touch


What is the expected result?

All finger-traces have a circle for both touch start and touch end.

What happens instead?

All finger traces get a circle for touch start, but only the first finger lifted gets one for touch-end.

Please use labels and text to provide additional information.

*** I've just marked this for Linux, but I haven't tested elsewhere so it may be more general.

Note: attempting to load the page in Release mode seems to crach the Renderer:

[1:1:0109/140136.988717:ERROR:variations_util.cc(102)] Missing Worker Pool Configuration: RendererBackground
abort: Sloppy function expects JSReceiver as receiver.
Received signal 11 <unknown> 000000000000
#0 0x7f1b2bf31dd4 base::debug::(anonymous namespace)::StackDumpSignalHandler()
#1 0x7f1b2c0b0330 <unknown>
#2 0x7f1b274dd8f4 v8::internal::Heap::Contains()
#3 0x7f1b275f261a v8::internal::HeapObject::HeapObjectShortPrint()
#4 0x7f1b275f243b v8::internal::Object::ShortPrint()
#5 0x7f1b2784f31b v8::internal::StringStream::PrintObject()
#6 0x7f1b2784ef43 v8::internal::StringStream::Add()
#7 0x7f1b274af073 v8::internal::JavaScriptFrame::Print()
#8 0x7f1b275a3e30 v8::internal::Isolate::PrintStack()
#9 0x7f1b275a58c4 v8::internal::Isolate::PrintStack()
#10 0x7f1b2782766b v8::internal::__RT_impl_Runtime_Abort()
#11 0x7f1b2782745e v8::internal::Runtime_Abort()
#12 0x33de8bf8426e <unknown>
  r8: 00007f1b22dea8e0  r9: 00007f1b22dcffb0 r10: 00007f1b22dea940 r11: 00007f1b228aa550
 r12: 8b4864fb89480000 r13: 00007f1b1dcb2691 r14: 00007ffcf87b24b0 r15: 00007f1b1dcb2691
  di: 8b4864fb89480000  si: 00007f1b1dcb2691  bp: 00007f1b22dd29b0  bx: 00007f1b1dc80000
  dx: 0000000000000006  ax: 8b4864fb89480000  cx: 0000000000000006  sp: 00007ffcf87b2410
  ip: 00007f1b274dd8f4 efl: 0000000000010206 cgf: 0000000000000033 erf: 0000000000000000
 trp: 000000000000000d msk: 0000000000000000 cr2: 0000000000000000
[end of stack trace]



For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.