Evaluate the use of an alternate JS engine for higher throughput about jsunpack-n HOT 2 OPEN

After patching I think changing line 301 from 

po = subprocess.Popen(['js', '-f', self.OPTIONS.pre, '-f', 
current_filename+'.js', '-f', self.OPTIONS.post], shell=False, stdout = 
js_stdout, stderr = js_stderr)

to 

po = subprocess.Popen(['d8', ' ', self.OPTIONS.pre, ' ', 
current_filename+'.js', ' ', self.OPTIONS.post], shell=False, stdout = 
js_stdout, stderr = js_stderr)

should do the job for v8. Shouldn't it?

This is a good idea and I've tested it myself to confirm it is effective. Even 
further speedup can be achieved by using the code as a library instead of 
launching a new process each time (effectively fork and exec copies the entire 
process memory).

I'd recommend that If you do make this engine change to make sure that you are 
still hooking the eval function. By default there are locations to do this in 
the existing code in the patch to spidermonkey (default on), and pre.js hooking 
(default off). If you decide to move away from spidermonkey, then just enable 
the pre.js eval hooking instead.