Implements iterator finalisation by desugaring for-of loops with an additional try-finally wrapper. See comment in parser.cc for details.

Also improved some AST printing facilities while there.

@Ross, I had to disable the bytecode generation test for for-of, because it got completely out of hand after this change (the new bytecode has 150+ lines). See the TODO that I assigned to you.

Patch set 1 is WIP patch by Georg (http://crrev.com/1695583003), patch set 2 relative changes.

@Georg, FYI, I changed the following:

- Moved try-finally out of the loop body, for performance, and in order to be able to handle `continue` correctly.
- Fixed scope management in ParseForStatement, which was the cause for the variable allocation failure.
- Fixed pre-existing zone initialisation bug in rewriter, which caused the crashes.
- Enabled all tests, adjusted a few others, added a couple more.

BUG=v8:2214
LOG=Y

Review URL: https://codereview.chromium.org/1695393003

Cr-Commit-Position: refs/heads/master@{#34111}