CI: run tests in browser

[IvanGoncharov]

We have some Node specific code in our codebase and it works fine but we can't fallback mechanism.
For example, we use Error.captureStackTrace if available but it's always available in Node so we never tested this code:

graphql-js/src/error/GraphQLError.js

Lines 203 to 210 in 576682f

	} else {
	Object.defineProperty(this, 'stack', {
	value: Error().stack,
	writable: true,
	configurable: true,
	});
	}
	}