How can I color the white corner with webkit-scrollbar?

Fiddle

I am using ::-webkit-scrollbar to make a custom scrollbar in Chrome. I have a border-radius: 10px and in doing that, there are white corners at the top:

Sorry, it's kinda hard to see since it's a scrollbar.

I want the corners to be the same color as the header div (#dadae3). Is there any way to get rid of the white corners using CSS only without changing the styles of the scrollbar?

CSS (entire):

body {
  padding: 0;
  margin: 0
}
::-webkit-scrollbar {
  width: 13px;
}
::-webkit-scrollbar-track {
  background: #ffffff;
  border-radius: 10px;
  border: 1px solid #aeaeb5
}
::-webkit-scrollbar-thumb {
  background: #dadae3;
  border-radius: 10px;
  border: 1px solid #aeaeb5
}
::-webkit-scrollbar-thumb:hover {
  background: #c4c4cc
}
::-webkit-scrollbar-thumb:active {
  background: #aeaeb5
}

HTML:

<div style='background: #dadae3; width: 100%; height: 30px;'></div>
<div style='width: 100%; height: 1000px'></div>

You have to set the ::-webkit-scrollbar-corner pseudo-element, e.g.

::-webkit-scrollbar-corner { background: rgba(0,0,0,0.5); }