- Use `path` module from browser process in sandboxed renderer. This is required
because the return value of `path.join` is platform-specific, and this is an
assumtion of crash-reporter.js which is shared between sandboxed and
non-sandboxed renderers.
- Set `process.platform` and `process.execPath` in sandboxed renderer
environment. This is required to spawn the windows crash service from
sandboxed renderer.
- Use a single temporary directory for all crashReporter tests. This is required
to make tests more deterministic across platforms(since mac's crashpad doesn't
support changing the crash dump directory). Also make a few improvements/fixes
to the `uploadToServer` test.
