* Property variance type annotations for Flow plugin
Non-method properties and indexers of object types, declare class, and
interfaces can be "positive" or "negative." Class fields, but again not
methods, can also have variance.
This PR generalizes the variance annotations for type parameters into a
new node type, and reuses that node for those properties.
The code for object types is reused for interfaces and declare classes.
The changes there are straightfoward.
The code for class fields is reused for object literals, which do not
support variance annotations (currently). This code is a bit sketchy,
because we always parse variance annotations in the `parsePropertyName`
extension, then error in a the subsequent parse phase for object
literals (`parseObjPropValue`) or class methods (`parseClassMethod`).
* Remove bogus unreachable code, clarify variance parsing conditional
* Don't use a new node type for variance annotations
Adding a new node type, specifically changing the TypeParameter node's
variance property to be node-valued, is a breaking change. We might
choose to make this breaking change in a later version.
* s/start/variancePos
Expanding on #150, this allows `unexpected()` to accept the expected token type instead of a message string.
This overload is then used in a couple more places (that independently implement a logic similar to `expect()`'s) to construct an `Unexpected token, expected FOO` message.
I also noticed that there was missing test coverage for builtin types,
so I added a test for that, which includes the newly added type as well
as the other existing types.
* Fix parsing object rest
This makes object-rest-spread behave according to spec and only
allow one rest operator and enforces it to be the last
param in the object.
Also move all object-rest-spread tests to a own folder.
* Show nicer error messages
* Rephrase "assigning/binding to rvalue" error messages with context (#119)
* Fix code style in parser/lval.js
* istanbul ignore some unused branches in parser/lval.js
* Fix code style again in parser/lval.js
