When the parent process has trouble deserializing an IPC message from the content
process, it originally killed that content process. This doesn't result in us
creating a crash report (and doing so is difficult if the FatalError is hit
off main thread). We now crash the parent process if we hit such a FatalError
in the parent process. This will hopefully give us an idea of how frequent
these FatalErrors are, since up until now we've been getting no crash data
for them.
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