Add Document.parseHTMLUnsafe / HTMLDocument.parseHTMLUnsafe and full DOM parsing coverage - #1121

Goal

Implement Document.parseHTMLUnsafe(html) as a static method on the Document class (and also on HTMLDocument) in HtmlUnit, and add a comprehensive test suite in DOMParserTest.java (or a new ParseHTMLUnsafeTest.java).

Background / Spec

Document.parseHTMLUnsafe(string) is defined in the HTML Living Standard §8.4 and DOM Parsing spec. It is a static method on Document that:

1. Takes a string of HTML markup
2. Parses it as a full HTML document (not a fragment)
3. Returns a new Document object (an HTMLDocument)
4. Does not sanitize the HTML (hence "Unsafe") — script content, event handlers, etc. are preserved in the parsed tree (though they are not executed)
5. The returned document has no browsing context (not attached to any window)
6. Unlike DOMParser.parseFromString(html, 'text/html'), this is a static method called directly on the Document constructor: Document.parseHTMLUnsafe("<html>...</html>")

Existing code to understand first

Before implementing, study these files carefully:

• src/main/java/org/htmlunit/javascript/host/dom/DOMParser.java — this already implements parseFromString for text/html, using StringWebResponse + HtmlPage + HTMLParser. The new parseHTMLUnsafe should reuse the same parseHtmlDocument static helper.
• src/main/java/org/htmlunit/javascript/host/dom/Document.java — this is where the new @JsxStaticFunction must be added.
• src/main/java/org/htmlunit/javascript/host/html/HTMLDocument.java — check if parseHTMLUnsafe also needs to be placed here (browsers expose it on both Document and HTMLDocument).
• src/main/java/org/htmlunit/javascript/host/URL.java — reference for @JsxStaticFunction pattern.
• src/main/java/org/htmlunit/javascript/host/media/MediaSource.java — another simple @JsxStaticFunction example.
• src/test/java/org/htmlunit/javascript/host/dom/DOMParserTest.java — existing test patterns to follow.

Implementation

1. Add parseHTMLUnsafe to Document.java

In src/main/java/org/htmlunit/javascript/host/dom/Document.java, add a static method:

/**
 * Parses the given string of HTML without sanitizing it and returns a new HTMLDocument.
 *
 * @param cx        the current context
 * @param scope     the scope
 * @param thisObj   the scriptable this object
 * @param args      the arguments
 * @param funObj    the function object
 * @return a newly created {@link HTMLDocument}
 *
 * @see <a href="/api/browser/proxy?url=https%3A%2F%2Fhtml.spec.whatwg.org%2Fmultipage%2Fdynamic-markup-insertion.html%23dom-parsehtmlunsafe">
 *     HTML spec - parseHTMLUnsafe</a>
 */
@JsxStaticFunction
public static HTMLDocument parseHTMLUnsafe(final Context cx, final VarScope scope,
        final Scriptable thisObj, final Object[] args, final Function funObj) {
    final String html = args.length == 0 || JavaScriptEngine.isUndefined(args[0])
            ? ""
            : JavaScriptEngine.toString(args[0]);

    final Window win = getWindow(funObj);
    // reuse DOMParser.parseHtmlDocument which already does the right thing
    try {
        final WebWindow webWindow = win.getWebWindow();
        final WebResponse webResponse = new StringWebResponse(html, webWindow.getEnclosedPage().getUrl());
        return (HTMLDocument) DOMParser.parseHtmlDocument(win.getDocument(), webResponse, webWindow);
    }
    catch (final IOException e) {
        throw JavaScriptEngine.reportRuntimeError("parseHTMLUnsafe failed: " + e.getMessage());
    }
}

Note: Check how DOMParser.parseHtmlDocument is called elsewhere — its first parameter is HtmlUnitScriptable scriptable. Pass win.getDocument() (which is an HtmlUnitScriptable) so the prototype/scope resolution works correctly.

Note: Also check whether parseHTMLUnsafe needs to live on HTMLDocument as well (browsers expose Document.parseHTMLUnsafe and HTMLDocument.parseHTMLUnsafe). If HTMLDocument extends Document in HtmlUnit's JS class hierarchy, inheriting the static may or may not work — check and add a separate @JsxStaticFunction override in HTMLDocument.java if needed, delegating to the same logic.

2. Required imports

Add whatever imports are needed in Document.java:

• org.htmlunit.StringWebResponse
• org.htmlunit.WebResponse
• org.htmlunit.javascript.host.dom.DOMParser (if not already imported)
• org.htmlunit.corejs.javascript.Context
• org.htmlunit.corejs.javascript.Function
• org.htmlunit.corejs.javascript.Scriptable
• org.htmlunit.corejs.javascript.VarScope

Test suite

Create src/test/java/org/htmlunit/javascript/host/dom/ParseHTMLUnsafeTest.java extending WebDriverTestCase with the following tests. Follow the exact style of DOMParserTest.java (inline HTML string, LOG_TITLE_FUNCTION, loadPageVerifyTitle2).

Tests to ...