Drop .textContent IE8 polyfill and rewrite escaping tests against public API (#11331)

* Rename escapeText util. Test quoteAttributeValueForBrowser through ReactDOMServer API

* Fix lint errors

* Prettier reformatting

* Change syntax to prevent prettier escape doble quote

* Name and description gardening. Add tests for escapeTextForBrowser. Add missing tests

* Improve script tag as text content test

* Update escapeTextForBrowser-test.js

* Update quoteAttributeValueForBrowser-test.js

* Simplify tests

* Move utilities to server folder