Let the treemap in the size analysis tool handle browser back buttons

After navigating into nodes of the treemap, one might be tempted to press the back button on the browser to return to the previous layer. Though that ends up closing the whole treemap and sending the user back to the analysis json upload page. Would be nice to handle it within the page and pop nodes in the treemap instead.

Start in the size analysis tool and trace how treemap nodes are entered and how the browser back action currently returns to the analysis JSON upload page. The work is done when browser back moves to the previously viewed treemap layer instead of closing the treemap, while normal navigation remains intact.

Vom Indexierungsmodell aus dem Issue-Text verfasst.