Added 2 extra let tests

These tests check for the temporal dead zone, and correct for-loop
iteration bindings. They are distinct from the basic let-test, as they
represent more advanced or nuanced functionality.
Altered the TDZ test to include const

Both const and let are subject to the temporal dead zone.
Fixed a small bug

Also updated IE11 support for for-loop iteration scope.
Const test now checks that assignment is an error

Assigning to a const should be a syntax error. This commit does not
update the test results to match this stricter test, yet.

This also fixes tabs introduced in previous commits.
Updating const results

Almost everything fails this updated test by treating const reassignment
as a silent failure instead of a syntax error.
Updated TDZ test results

Also fixed a bug in the Node test script.
Fixed Traceur result for the let-for test

Also made the test's code less wide.
Added explanatory notes about let/const support
Added an anti-hoisting check to the const test

I was previously hesitant to include this, but since most platforms'
const support is invalidated already by their lack of error-throwing,
adding this check doesn't disturb the results at all.