Type specificity in API parameters

We may be too optimistic in ignoring JS vs. TS typing issues in APIs, e.g.

```ts
// Element.ts
public setAttribute(name: string, value: string): void {...}
```

In this example, there's no type conversion if a caller passes in a number or other non-string type.

```js
const el = document.createElement('p');
el.setAttribute('data-foo', 123);
el.getAttribute('data-foo'); // Expected: "123", actual: 123.
```

Start in Element.ts at setAttribute and trace how its value reaches getAttribute. Compare the TypeScript declaration with the JavaScript runtime behavior shown in the issue, then identify the API cases that need consistent type handling. Done means non-string input produces the expected string value without breaking the existing API behavior.

Written by the indexing model from the issue text.