The diff toggle carried the replaceState handler as literal text in two attributes, with the reasoning in a comment above them. Both move onto a syncurl helper, so the next surface that needs it gets the try/catch and the replaceState-not-pushState choice for free instead of by copy-paste. Emitted markup is unchanged.

The helper neutralizes quotes in the fragment URL: it lands inside a JS string inside an attribute built as HTMLAttr, where escaping is off. check-in: 058a2216c9 user: dmestas tags: url-sync-helper