#### Support literal initializers and multiple declarations in `DeclareVariable` (#18929 by @fisker)

<!-- prettier-ignore -->
```flow
// Input
declare const x: string, y: number;
declare const s = 'foo';

// Prettier stable
SyntaxError: Unexpected token `,`, expected the token `;` (1:24)

// Prettier main
declare const x: string, y: number;
declare const s = "foo";
```
