Fix Markdown code block editor iframe bootstrap

Use the permitted empty webview bootstrap for nested frames and update @vscode/markdown-editor to 0.0.2-90, which forwards the bootstrap URL to physical iframes.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: cf6761b4-5164-41c7-8123-5da286a9798a

Author: hediet

extensions/markdown-language-features/markdown-editor-src/editor.ts

@@ -248,11 +248,14 @@ class Editor extends Disposable {
 	#createView(host: HTMLElement, content: string): void {
 		const model = this.model;
 		const scriptNonce = document.querySelector<HTMLMetaElement>('meta[name="vscode-markdown-editor-script-nonce"]')?.content;
+		const iframeBootstrapUrl = new URL(location.href);
+		// Nested frames must use the empty webview bootstrap, not the restricted index.html entrypoint.
+		iframeBootstrapUrl.pathname = '/fake.html';
 		const embeddedCodeEditorFactory = this._register(new VirtualizedIframeEmbeddedEditorFactory({
 			providers: this.#createIframeProviders(this.#codeBlockEditorProviders),
 			scriptNonce,
 			themeCss: () => `:root { ${document.documentElement.getAttribute('style') ?? ''} }`,
-			iframeBootstrapUrl: location.href,
+			iframeBootstrapUrl: iframeBootstrapUrl.href,
 			onAmbiguous: (language, providers) => this.#vscode.postMessage({
 				type: 'codeBlockEditorDiagnostic',
 				message: `Ambiguous providers for ${language}: ${providers.map(provider => provider.id).join(', ')}`,

extensions/markdown-language-features/package-lock.json

@@ -1791,7 +1791,7 @@
   },
   "dependencies": {
     "@vscode/extension-telemetry": "^0.9.8",
-    "@vscode/markdown-editor": "^0.0.2-88",
+    "@vscode/markdown-editor": "^0.0.2-90",
     "@vscode/observables": "^0.1.1-0",
     "dompurify": "^3.4.10",
     "highlight.js": "^11.8.0",