[Full Changelog](https://github.com/matrix-org/matrix-js-sdk/compare/v0.7.3...v0.7.4-rc.1) * Remove babel-polyfill [\#321](https://github.com/matrix-org/matrix-js-sdk/pull/321) * Update build process for ES6 [\#320](https://github.com/matrix-org/matrix-js-sdk/pull/320) * 'babel' is not a babel package anymore [\#319](https://github.com/matrix-org/matrix-js-sdk/pull/319) * Add Babel for ES6 support [\#318](https://github.com/matrix-org/matrix-js-sdk/pull/318) * Move screen sharing check/error [\#317](https://github.com/matrix-org/matrix-js-sdk/pull/317) * release.sh: Bail early if there are uncommitted changes [\#316](https://github.com/matrix-org/matrix-js-sdk/pull/316)