Include Comment nodes in polyfill hook types

[olavoasantos]

Problem

The polyfill invokes text and child-mutation hooks for Comment nodes at runtime, but the corresponding Hooks TypeScript signatures accepted only Text nodes. The public type contract therefore rejected a runtime-supported node kind.

Impact

Minor. TypeScript consumers implementing setText, insertChild, or removeChild could not accurately type their handling of comments. This is type-contract drift rather than a runtime failure, but it can force unsafe casts or make valid hook implementations fail type checking.

Reproduction

const comment = document.createComment('Comment');

parent.appendChild(comment);
comment.data = 'Updated comment';
parent.removeChild(comment);

The added regression test verifies that runtime calls already pass the Comment node to insertChild, setText, and removeChild. Before this change, the type-level assertions that a Document['createComment'] result is accepted by those hook parameter types failed; they now pass.

Change

Widen the affected hook parameters from Text to Text | Comment, matching the nodes the polyfill already supplies at runtime. No hook dispatch behavior changes.

Tests

Adds compile-time assertions for comment compatibility with all three hook signatures, plus runtime spies that verify insertion, text updates, and removal receive the comment node and expected payloads.

Stack

• Stack: Independent quick wins (#702), layer 4 of 4
• Base: normalize-text-node-hooks
• Review after PR Normalize createTextNode hook data #690.

Validation

Fresh GitHub CI on restacked head 08e3223 passes:

• lint;
• type-check and build;
• unit tests with coverage;
• bundle-size checks;
• Playwright end-to-end tests;
• the classified Web Platform Test suite.