Add support for for...of loops
Add tests for for...of loop
Add for...of support to the Codegen
Merge branch 'forof' of https://github.com/sankha93/dynjs into sankha93-forof
Add a Jasmine test for ES6 for..of loops on Arrays.

This test caught the error in `BasicInterpretingVisitor` where the value
of the Reference should have been used rather than the Reference object.