Segfault with double free using std.read (having multiple concurrent promises?) #71
Description
The test is in tests/test-issue-0071.js
$ jk run test-issue-0071.js
*** Error in `jk': double free or corruption (out): 0x00007fee98000a20 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7feea100e7e5]
/lib/x86_64-linux-gnu/libc.so.6(+0x8037a)[0x7feea101737a]
/lib/x86_64-linux-gnu/libc.so.6(cfree+0x4c)[0x7feea101b53c]
jk(_ZN2v88internal20ArrayBufferCollector15FreeAllocationsEv+0x8e)[0xf9269e]
jk(_ZN2v88internal20ArrayBufferCollector11FreeingTask11RunInternalEv+0x146)[0xf92946]
jk(_ZN2v88platform12WorkerThread3RunEv+0x36)[0x9cdf16]
jk[0xe05880]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba)[0x7feea1c096ba]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7feea109e41d]