Bug: SSR of malformed? `meta` renders nothing(working in 18.2)

<!-- Please provide a clear and concise description of what the bug is. Include screenshots if needed. Please test using the latest version of the relevant React packages to make sure your issue has not already been fixed. --> React version: ## Steps To Reproduce 1. SSR `<meta name="test" />` (`renderToString` and `renderToReadableStream`) <!-- Your bug will get fixed much faster if we can run your code and it doesn't have dependencies other than React. Issues without reproduction steps or code examples may be immediately closed as not actionable. --> Link to code example: - Working in 18.2: https://codesandbox.io/s/18-2-ssr-meta-only-working-t6lxvw - render nothing in 18.3-5fcf1a4b4c2150a1b9fe0de0144a82a053c63966: https://codesandbox.io/s/18-3-5fcf1a4b4c2150a1b9fe0de0144a82a053c63966-ssr-meta-only-bug-woguy0?file=/src/index.js ## The current behavior Renders empty string ## The expected behavior Renders `<meta name="test" />` Don't know if that's a valid use case but it should at least warn that the meta tag is malformed? This broke the attribute fixture (originally reported in https://github.com/facebook/react/pull/25927). Also: 1. `<meta name="description" content={content} />` renders nothing unless `content` is a string. 1. `<meta http-equiv />` i.e. any `http-equiv` usage no longer renders anything. It used to warn at least.