The close settled on auxclick delivery, which the browser redirects to the
nearest common ancestor of the press/release targets when they differ — any
drift, middle-button autoscroll scroll, or tab-list reflow between press and
release swallowed the close (the strip hides its scrollbar, so Chrome's
autoscroll indicator is inert here and only added confusion).
Now the press target is recorded on middle mousedown (preventDefaulted to
disarm autoscroll at the source) and the close settles on the first middle
mouseup OVER that same tab — release-position semantics matching VS Code
(microsoft/vscode#101028) and user expectations for Chrome tabs
(crbug/40679924): pressing on a tab and releasing elsewhere cancels.
Left-button activate/drag and wheel scrolling are untouched
(tests/tab-bar-middle-click.spec.tsx).
Cold Cloud
76aacddbb9