Drag into Iframe doesn't see mouseup event

[charlesh88]

Replicate

1. Create and/or navigate to a Web Page view, which uses an Iframe.
2. Click and drag to resize and expand the tree view. Observe that as you drag to the right into the Iframe's area, the tree pane will stop resizing.
3. Release the mouse to "stop" dragging, and move your cursor back into the tree area; as you do so, observe that the tree will shrink as you move the cursor (as though the mouse is still down and dragging), even though the mouse button is no longer being held down.

The same phenomena occurs when expanding the size of the Inspector pane.

Expected behavior: the user should be able to resize the pane via dragging as normally and as seen in other view types. Marking as critical as this is manifesting while utilizing newly integrated components that utilize Iframes.

[kobe1104]

Verified fixed. Testathon 8/3/2021

[jvigliotta]

Verified: Testathon - 8/3/2021

[nikhilmandlik]

Verified Fixed.