The type checker had to do extensive work in resolving the
`NodePath.get` method call for the `NodePath` that had an intersection
type of `ts.VariableDeclarator&{init:t.Expression}`. The `NodePath.get`
method is typed using a conditional type which became expensive to
compute with this intersection type. As a workaround, the original
`init` property is explicitly omitted which avoids the performance
cliff. This brings down the compile time by 15s.
PR Close#39707
This commit adds the basic building blocks for linking partial declarations.
In particular it provides a generic `FileLinker` class that delegates to
a set of (not yet implemented) `PartialLinker` classes.
The Babel plugin makes use of this `FileLinker` providing concrete classes
for `AstHost` and `AstFactory` that work with Babel AST. It can be created
with the following code:
```ts
const plugin = createEs2015LinkerPlugin({ /* options */ });
```
PR Close#39116
JoostK
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