Browsing around in VisualEditor with <https://gerrit.wikimedia.org/r/322812> applied:
### Breaking
* [ ] JQMIGRATE: jQuery.fn.removeAttr no longer sets boolean properties: required
- https://jquery.com/upgrade-guide/3.0/#breaking-change-removeattr-no-longer-sets-properties-to-false
- When: Opening Reference insert dialog (stack: `OO.ui.TextInputWidget.setRequired / .. / ve.ui.MWReferenceDialog.initialize`)
- When (2): Saving changes (stack: `OO.ui.TextInputWidget.setRequired / .. / ve.ui.MWSaveDialog.initialize`)
* [ ] {icon exclamation-triangle color=red} Uncaught TypeError: Cannot assign to read only property 'left' of object '#ClientRect'
- When: Selecting text and creating a link (stack: `Object.OO.ui.Element.static.getRelativePosition / .. / OoUiPopupWidget.OO.ui.PopupWidget.setAlignment / VeUiDesktopContext.ve.ui.DesktopContext.updateDimensions`)
- When (also): Double-click an HTML Comment node in the surface for editing. After this the inspector can't be closed and most surface interactions are broken. {F6678336}
### Deprecated
Will not be removed in jQuery 3.0, but warned for as long as jQuery Migrate enabled.
* [x] `JQMIGRATE: jQuery.expr.filters is now jQuery.expr.pseudos`
- https://jquery.com/upgrade-guide/3.0/#deprecated-jquery-expr-quot-quot-and-jquery-expr-filters
- Stack: `OO.ui.isFocusableElement / .. / ve.ui.MWMediaDialog.initialize`
- When: Opening Media insert dialog