Add others vm hooks to allow mocking dependencies

[danieljoppi]

Add vm.runInNewContext: the same implementation of @laurentgoudet in #294 (fixes #293)
Add vm.runInContext: its very similar a vm.runInNewContext
and
Add support to Script.runInContext to fixes #254

[danieljoppi]

@gotwarlost I was think ... We can remove this hooks: vm.runInContext, vm.runInNewContext and vm.runInThisContext .

All there functions using vm.createScript - look:

• vm.runInContext: nodejs/master/lib/vm.js#exports.runInContext

exports.runInContext = function(code, contextifiedSandbox, options) {
  var script = new Script(code, options);
  return script.runInContext(contextifiedSandbox, options);
};

• vm.runInNewContext: nodejs/master/lib/vm.js#exports.runInNewContext

exports.runInNewContext = function(code, sandbox, options) {
  var script = new Script(code, options);
  return script.runInNewContext(sandbox, options);
};

• vm.runInThisContext: nodejs/master/lib/vm.js#exports.runInThisContext

exports.runInThisContext = function(code, options) {
  var script = new Script(code, options);
  return script.runInThisContext(options);
};

We only needed hook the vm.createScript.

[gotwarlost]

Not true - those other functions use the script constructor directly - they don't use createScript

[gotwarlost]

Move these assignments to top-level variables so that they are initialized early - otherwise by the time someone calls hookCreateScript - the original values could have been re-assigned.

[danieljoppi]

ok

[geovanisouza92]

What's the state about this?

I'm trying to test scripts that will be run on a embedded v8 context. So, I'm using Jest using Script.runInContext with mocked globals. The tests works, but no coverage is collected.