* Test runner: Detect extra property in 'actual' but not in 'expected'.
Also update all expected.json where this would result in errors.
* Include rmExpected.js script in case it is needed again
* 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
The primary goal of this commit is to add the ability to parse type parameter
declarations with defaults, like `type Foo<T = string> = T`. While I was in the
code, I fixed a few small things, like
* Type parameter declarations need 1 or more type parameters.
* The existential type `*` is not a valid type parameter.
* The existential type `*` is a primary type
* The param list for type parameter declarations now consists of
`TypeParameter` nodes
