…espace when integrating threads during profile processing, and add an upgrader to fix this mistake on existing processed profiles.

name, dur and title are properties of TracingMarker, not of the payload that is
inside the tracing marker. RedirectURI is optional.

Here's the code that writes out the payload to the JSON:
https://searchfox.org/mozilla-central/rev/9abd7f512c9b29071776e7ba3f991d5b5fd59ff6/tools/profiler/core/ProfilerMarkerPayload.cpp#164-201

…1546)

This PR contains four changes:

 1. Add a network marker to the profiling upgrading fixtures
 2. Fix the timestamps during processing and add an upgrader.
 3. Fix the flow types for Network marker payloads.
 4. Add a test for marker time shifting during profile processing.

When using only the opacity, the panel is visible from the accessibility
tree. Using `visibility: hidden` at the right place hides it when it's closed.

…file

An upcoming commit will hide the tab when there is no JS tracer
information available.