"Assertion `time == global_time' failed" with spidermonkey arm simulator

I built rr from source on this commit:

commit cdb22ede3c3039950a77c77e05044f3fd01411ca
Author: Robert O'Callahan <robert@ocallahan.org>
Date:   Tue Aug 9 18:20:16 2016 +1200

    Awk string indices start at 1

I did a ninja-build test and all tests passed.

On Fedora with this kernel:

$ uname -a
Linux localhost.localdomain 4.6.5-300.fc24.x86_64 #1 SMP Thu Jul 28 01:10:12 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

On this branch: https://github.com/fitzgen/gecko-dev/tree/rr-assertion-failure-test-case

Build the arm simulator like so:

$ ./js/src/devtools/automation/autospider.py --objdir $OBJDIR --build-only arm-sim

And then run like this:

bash-4.3$ ./js/src/tests/jstests.py $OBJDIR/dist/bin/js shell/futex.js -o --rr
## shell/futex.js: rc = -9, run time = 150.001963
Sleeping for 2 seconds
Waking the main thread now
Woke up as I should have in 2.011s
Main thread waiting on wakeup (2s)
Woke up as I should have in 2.011s
Starting outer wait
In the interrupt, starting inner wait with timeout 2s
Got the interrupt exception!
Script runs for too long, terminating.
TIMEOUT - shell/futex.js
[0|1|1|0] 100% ==========================================================>| 150.1s
TIMEOUTS
    shell/futex.js
FAIL
bash-4.3$ rr replay
rr: ../src/TraceStream.cc:543: void rr::TraceReader::read_generic(vector<uint8_t> &): Assertion `time == global_time' failed.
bash-4.3$ 

Reproduce the failure using the arm-sim build command, shell/futex.js, and rr replay; then inspect TraceStream.cc around line 543 and the recorded trace handling involved in the assertion. Run ninja-build test and confirm that replaying this case no longer fails with Assertion time == global_time' failed`.