PDF Toolbar disappears when window is resized below a certain width

Description
When a WebView2 control is hosted on a WPF window and the part of the window hosting the WebView2 is reduced below a certain width, the Toolbar for PDF documents disappears.

Version
SDK: 10.0.902.49
Runtime: n/a
Framework: WPF
OS: n/a or unknown (Windows 10 on developer machine)

Repro Steps
Create a resizable WPF window and host a WebView2 control in a grid column with width "*" so that it resizes with the window.
Host a PDF document in the WebView2. As far as we can tell it doesn't matter whether you set its source or navigate to a HTML page containing an object tag referencing the PDF.
Start with a large enough width and start resizing the width down.

Expected behaviour:
The toolbar should remain visible for much longer. Perhaps start reducing its size when the WebView2 goes below a certain width. If the width becomes so small that the Toolbar can no longer reasonably be displayed have some way of alerting the user why this is. Perhaps a warning triangle where the toolbar should be with a tooltip on it?

Actual behaviour:
Toolbar simply disappears

AB#35569824

Start by reproducing the issue in a resizable WPF window with a WebView2 control hosted in a star-sized grid column and a PDF document loaded. Compare toolbar behavior as the control narrows; done means the PDF toolbar remains visible at practical widths or clearly communicates why it cannot be displayed.