Reorder literal test batches.
Rephrase literal tests again.

I think the longer, more descriptive / talkative messages are better
suited for more complex tests. Simple tests should have simple messages.
Create expressions test suite with a couple initial tests.
Make emit (undefined) emit a node of type 'undefined'.

Makes expressions.js / 'Call with name expression as callable and no arguments' test pass.
Create binary expression tests.
Order test suites using number prefixes.

Since suites are executed in alphabetical order, prefixing them with
numbers allows us to decide in which order they execute.

js-emitter tests build up on previous ones. If suites don't run in this
order and basic functionality is broken, it will break more complex tests
instead of simple ones targetted at testing the basic functionality
itself, which are easier to understand.
Rephrase name expression vow.
Create empty and undefined nodes test suite.
Create unary expression tests.
Check unary operator before emitting.

Makes 015-expressions.js / Unary / 'Invalid operator' test pass.
Create invalid binary operator test.
Check binary operator before emitting.

Makes 015-expressions.js / Binary / 'Invalid operator' test pass.
Create basic statements test suite.
Allow block statements property to be undefined or non-array.

Makes 020-basic-statements.js / Blocks / 'Empty block' test pass.