Add JAWSM

Author: drogus

helpers/jawsm.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+node ../jawsm/runner/index.js "$@"

scripts/engines/jawsm.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+git clone https://github.com/drogus/jawsm.git --depth 1
+
+cd jawsm
+git rev-parse HEAD >../version.txt
+
+cargo build --release
+
+cd ..
+
+./scripts/test262.sh njs "$(pwd)/helpers/jawsm.sh" 8