Using HTML slots to render platform views in the web

Summary

Context

Description of change

Before
After

Migration guide

Code
Tests

Timeline

References

Summary

Flutter now renders all web platform views in a consistent location of the DOM,
as direct children of flt-glass-pane (regardless of the rendering backend:
html or canvaskit). Platform views are then “slotted” into the correct
position of the App’s DOM with standard HTML features.

Up until this change, Flutter web would change the styling of the rendered
contents of a platform views to position/size it to the available space. This
is no longer the case. Users can now decide how they want to utilize the space
allocated to their platform view by the framework.

Context