Fix Trusted Types violation (round #1)

[jrieken]

This is part of the TrustedTypes effort (see #103699) and a list of innerHTML usages which we avoid. To compile a list of violations

• run yarn web --trusted-types
• open http://localhost:8080/ in Edge or Chrome
• open console and check for "[Report Only] This document requires 'TrustedHTML' assignment."-messages

Also, there is .vscode/searches/TrustedTypes.code-search which finds all occurences of innerHTML. There are common sources of violation and therefore common fixes

• styling via style.innerHTML ➡️ use textContent instead (example c112f84)
• clear a node via node.innerHTML = '' ➡️ use dom.ts#clearNode or node.innerText = ''
• building dom nodes ➡️ use dom.$ or document.createElement and friends

---

• abstractTextMateService.js:250 @alexdima
• abstractTree.js:1075 @joaomoreno
• codiconStyles.js:17 @aeschli
• compositePart.js:277 @jrieken
• dirtydiffDecorator.js:1020 @joaomoreno
• explorerView.js:628 @isidorn
• listWidget.js:634 @joaomoreno
• menubar.js:419 @sbatten
• sash.js:35 @joaomoreno
• statusbarColorProvider.js:74 @bpasero
• statusbarPart.js:497 @bpasero
• viewLayer.js:394 @alexdima <-- will not happen, this is part of fine-tuned editor rendering, building dom nodes is not an option
• watermark.js:105 @chrmarti
• workbenchThemeService.js:560 @aeschli

[jrieken]

fyi @annkamsk