The height of the "DropDown" list for the combobox control can't be reset default height after called the " comboBox1.Items.Clear();" method

**OS** : RS4 X64+.Net 4.8.03316
**VS** : Dev16 d16.0stg 16.0 Preview 3 28505.103

**More info:**
1. This issue can reproduce from VS Dev10 to Dev16.
2. This issue can't reproduce when adding the following code to Form1.Designer.cs.
```
comboBox1.Items.AddRange(new object[] { "a", "b", "c", "d", "e" });
comboBox1.Items.Clear();
```
**Steps to reproduce:**
1. Create a Winforms application.
2. Drag a Combobox control to form designer.
3. Add the following code to Form1.cs.
```
private void Form1_Load(object sender, EventArgs e)
{
comboBox1.Items.AddRange(new object[] { "a", "b", "c", "d", "e" });
comboBox1.Items.Clear();
}
```
**Actual:**
The height of the "DropDown" list for the combobox control can't be reset default height after called the " comboBox1.Items.Clear();" method.

**Expected:**
The height of the "DropDown" list for the combobox control should be reset default height after called the " comboBox1.Items.Clear();" method.