Preserve canonical DOM identity through SameObject getters

[PrzemyslawKlys]

MutationRecord.target currently gets a new proxy projected as INode, losing the element API and the canonical wrapper used elsewhere. Reuse GetDomNode for node/window values returned by DomSameObject getters so the concrete prototype, strict identity and script-owned properties are preserved. Other SameObject values retain the existing cache.

Fixes #140.

The regression exposes an attribute mutation record to Jint and checks target.id, target === document.body, and an expando written through document.body. It fails on unmodified devel and passes with this fix.

This reusable binding defect was encountered by the public OfficeIMO HTML runtime. The patch has no OfficeIMO dependency and requires no downstream change or coordinated release to test.

Prerequisites

• I have read the CONTRIBUTING document
• My code follows the code style of this project

Contribution type

• Bug fix (non-breaking)
• Added regression coverage
• Added a pending changelog note
• New and existing tests passed locally on .NET 10: 301 tests

netstandard2.0 build also passed with zero warnings/errors. Local validation used macOS arm64, SDK 10.0.303, AngleSharp 1.8.0 and Jint 4.15.3. Windows/Linux validation is left to the repository CI.

[CLAassistant]

All committers have signed the CLA.

[FlorianRappl]

LGTM - we just need to put it into a 1.1.1 version