Fix display for nodes

[macmv]

This Pull Request fixes/closes #1311

This is a collection of fixes for the fmt::Display functions on various nodes. With this PR, you can print a StatementList to stdout in nearly the same format as the source code.

[Razican]

Thank you for these contributions!! This will look much better now. Could we add some tests to make sure new changes don't break it?

[macmv]

Tests take a long time to write. I'm going to work on this later tonight. I put all the tests I've written so far in the tests.rs file in each node directory (for example, syntax/ast/node/call/tests.rs). There is also a utility function for testing all of these, which is at the bottom of syntax/ast/node/mod.rs. I wasn't really sure where else to put it, and I made sure its #[cfg(test)].

[Razican]

Tests take a long time to write. I'm going to work on this later tonight. I put all the tests I've written so far in the tests.rs file in each node directory (for example, syntax/ast/node/call/tests.rs). There is also a utility function for testing all of these, which is at the bottom of syntax/ast/node/mod.rs. I wasn't really sure where else to put it, and I made sure its #[cfg(test)].

Something that could simplify writing the tests would be to add a folder with some code snippets to test. That way, you can just load each of them in a test and compare the outputs.

[macmv]

I think setting up a loader for a bunch of files would just take more time. The most time-consuming part of these tests was just setting up the testing function, and re-writing my previous tests.

[Razican]

Test262 conformance changes:

Test result	master count	PR count	difference
Total	78,897	78,897	0
Passed	26,857	26,858	+1
Ignored	15,628	15,628	0
Failed	36,412	36,411	-1
Panics	0	0	0
Conformance	34.04%	34.04%	+0.00%

Fixed tests:

test/built-ins/Map/prototype/set/append-new-values-normalizes-zero-key.js (previously Failed)

[macmv]

Alright, I've finished up the tests. The world is beautiful, and everything passes, and a lot of bugs were fixed. I think I covered everything, but tarpaulin is hard to use, so I am not entirely sure that I didn't miss something.

[RageKnify]

Minor thing to avoid compiler warnings the rest looks great.

[Razican]

I think this is almost ready. Great work!!! Check my comment and @RageKnify's :)

[macmv]

I've fixed both of those issues. Thank you for pointing those out. Also, cargo fix didn't do anything except remove that unused import, so I don't think there are any other warnings I created.