This PR introduces support for importing JSON based profiles that are missing a terminating `]` (and possibly have an extraneous `,`).
This is similar to #202, but takes a much more targeted and simple approach.
I'm confident that this approach is sufficient because this is exactly what `chrome://tracing` does: 27e047e049/tracing/tracing/extras/importer/trace_event_importer.html (L197-L208)Fixes#204
