Our convention is that AST type fields are ordered in order they appear in source. Move `type_parameters` fields in TS function declaration types to before `this_param` and formal parameters.
Make naming of temp vars follow Babel. It wasn't apparent that our version of this transform was behaving differently from Babel because the Babel plugin has very few tests. The added tests replicate Babel's output.
Fix exponentiation operator transform to bail out early if a private class property.
We can't transform this:
```js
class C {
#p;
method() {
this.#p **= 2;
}
}
```
But we should at least leave it alone. Previously `get_obj_ref` called `ast.move_expression(expr)` on the member expression's object before bailing out, so example above was transformed to:
```js
class C {
#p;
method() {
null.#p **= 2; // <-- `null`
}
}
```
This PR makes it spot this case early and bail out *before* calling `ast.move_expression(expr)`.
Closes#5020.
`TraverseCtx::generate_uid` and associated methods return a `BoundIdentifier`, containing both symbol ID and name. This reduces boilerplate code for the caller and avoids and unnecessary lookup to get the name.
Also add a couple of helper methods to `BoundIdentifier` to reduce boilerplate further.
First step towards #5049.
Various transforms need to add a `var` statement at top of enclosing statement block.
e.g.:
```js
// Input
a ??= b;
```
```js
// Output
var _a;
(_a = a) !== null && _a !== void 0 ? _a : (a = b);
```
Each of these transforms previously maintained it's own stack and added `var` statements individually.
Share this functionality in a "common" utility transform which maintains a single stack to serve them all.
