Add basic HTMLIframeElement support for DOM creation and recognition

[Copilot]

This PR implements basic HTMLIframeElement support in JSAR Runtime, enabling developers to create and use <iframe> elements structurally within JSAR applications without embedded content functionality.

What's Implemented

• Element Creation: Support for document.createElement('iframe')
• DOM Integration: Iframe elements can be appended to the DOM tree and queried using standard DOM APIs
• Attribute Support: Standard iframe attributes (src, width, height, etc.) can be set and retrieved
• CSS Styling: Iframe elements inherit full styling capabilities from HTMLElement with block-level display

Usage Examples

// Create iframe programmatically
const iframe = document.createElement('iframe');
iframe.src = 'about:blank';
iframe.width = '300';
iframe.height = '200';
document.body.appendChild(iframe);

// Query iframe elements
const iframes = document.querySelectorAll('iframe');
const myIframe = document.getElementById('iframe-id');

<!-- Use iframe in HTML -->
<iframe src="about:blank" width="400" height="300"></iframe>

Implementation Details

The implementation follows the established pattern used by other HTML elements in JSAR:

• C++ Classes: HTMLIframeElement inherits from HTMLElement providing core functionality
• JavaScript Bindings: Exposes HTMLIFrameElement constructor to JavaScript environment
• Registration: Added to TYPED_ELEMENT_MAP for automatic element factory creation
• Browser Compatibility: Added to browser compatibility data at docs/api/browser-compat-data/html/elements/iframe.json

Intentional Limitations

As specified in the requirements, this implementation provides structural support only:

• ❌ Content loading from src URLs
• ❌ iframe content rendering
• ❌ Sandboxing and security isolation
• ❌ Cross-origin restrictions

Iframe elements are treated as regular DOM elements that can be created, styled, and positioned, but do not load or display any content.

Fixes #157.

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[yorkie]

Please remove this lock file.

[Copilot]

Removed yarn.lock file as requested. 411ddef

[yorkie]

iframe's display should be block.

[Copilot]

Changed iframe display style from "inline-block" to "block" as requested. 411ddef

[yorkie]

No need to test iframe element, please remove this file.

[Copilot]

Removed fixtures/html/iframe-test.html file as requested. 411ddef

[yorkie]

Remove this file.

[Copilot]

Removed docs/HTMLIframeElement.md file as requested. 411ddef

[yorkie]

:)

[yorkie]

@copilot Please update the docs.

[yorkie]

@copilot Update again

[Copilot]

@copilot Please update the docs.

Updated documentation by adding browser compatibility data for iframe element at docs/api/browser-compat-data/html/elements/iframe.json. 411ddef

@copilot Update again

Documentation updated with browser compatibility data for iframe element support. 411ddef