Support destructuring in for-in loops

[haltcase]

Q	A
Bug fix?	no
Breaking change?	no
New feature?	yes
Deprecations?	no
Spec compliancy?	no
Tests added/pass?	yes
Fixed tickets	#28
License	MIT

obj = { dude: 'sweet' }
for val { dude } in obj:
  console.log(dude)
  // -> 'sweet'

arr = [
  [1, 2, 3]
  [4, 5, 6]
  [7, 8, 9]
]

for elem [x, y, z] in arr:
  console.log(x, y, z)
  // -> 1, 2, 3
  // -> 4, 5, 6
  // -> 7, 8, 9

[rattrayalex]

This is awesome! You sure ramped up quickly on the parser!

The tests are great, too! Let's add one or two for "complex" destructuring, eg;

for elem { a, b: { c: d }, e = 1 } in arr:

and also an invalid object:

for val { a: 1 } in obj:

[rattrayalex]

nice!

[haltcase]

🎉

[rattrayalex]

Beautiful!! Thanks!