Error of go-v8

gistfile1.txt

#
# Fatal error in HandleScope::HandleScope
# Entering the V8 API without proper locking in place
#

SIGABRT: abort
pc: 0x7fff8c1c8212


goroutine 1 [chan receive]:
testing.RunTests(0x2000, 0x1ecfb8, 0x400000004, 0x28d01, 0x2786f40, ...)
  /Users/surma/.homebrew/Cellar/go-src/1.0.3/src/pkg/testing/testing.go:369 +0x7b8
testing.Main(0x2000, 0x1ecfb8, 0x400000004, 0x1ecc50, 0x200000002, ...)
	/Users/surma/.homebrew/Cellar/go-src/1.0.3/src/pkg/testing/testing.go:304 +0x7a
main.main()
	github.com/voxelbrain/go-v8/_test/_testmain.go:53 +0x91

goroutine 2 [syscall]:
created by runtime.main
	/Users/surma/.homebrew/Cellar/go-src/1.0.3/src/pkg/runtime/proc.c:221

goroutine 3 [chan send]:
github.com/voxelbrain/go-v8._func_003()
	github.com/voxelbrain/go-v8/_test/_cgo_gotypes.go:93 +0x3b
created by github.com/voxelbrain/go-v8.init·1
	github.com/voxelbrain/go-v8/_test/_cgo_gotypes.go:96 +0x24

goroutine 5 [syscall]:
github.com/voxelbrain/go-v8._Cfunc_v8_create(0xb9a80, 0xf840044c80)
	github.com/voxelbrain/go-v8/_test/_cgo_defun.c:58 +0x2f
github.com/voxelbrain/go-v8.NewContext(0x120e80, 0xf840063220)
	github.com/voxelbrain/go-v8/_test/_cgo_gotypes.go:222 +0x3e
github.com/voxelbrain/go-v8.TestAddFunc(0xf840069f00, 0x14fb3358)
	/Users/surma/src/github.com/voxelbrain/go-v8/v8_test.go:52 +0x4c
testing.tRunner(0xf840069f00, 0x1ecfd0, 0x0, 0x0)
	/Users/surma/.homebrew/Cellar/go-src/1.0.3/src/pkg/testing/testing.go:292 +0x6f
created by testing.RunTests
	/Users/surma/.homebrew/Cellar/go-src/1.0.3/src/pkg/testing/testing.go:368 +0x795
rax     0x0
rbx     0x6
rcx     0x7fff5fbff228
rdx     0x0
rdi     0x303
rsi     0x6
rbp     0x7fff5fbff250
rsp     0x7fff5fbff228
r8      0x7fff76b05278
r9      0x7fff5fbfebd0
r10     0x20000000
r11     0x206
r12     0x2441ea1
r13     0xf8400427d0
r14     0x7fff76b06180
r15     0x2441eba
rip     0x7fff8c1c8212
rflags  0x206
cs      0x7
fs      0x0
gs      0x0
exit status 2
FAIL	github.com/voxelbrain/go-v8	0.020s
```

After a little investigation it turns out, that the following (new) test fails as well:

```Go
func TestMultipleContexts(t *testing.T) {
	_ = NewContext()
	_ = NewContext()
}