remove unneccessary double-polyfills from runtime

[FredKSchott]

From the babel-polyfill docs:

Babel includes a polyfill that includes a custom regenerator runtime and core-js.

This will emulate a full ES2015+ environment and is intended to be used in an application rather than a library/tool. This polyfill is automatically loaded when using babel-node.

ripple-lib is already using babel to transpile all advanced features and add necessary polyfills, so loading "babel-polyfill" additionally is unnecessary. Worse, it means that all polyfills are being double-loaded and potentially double-executed.

Removing this line results in a much smaller build (ripple-latest.js 1.4MB vs 1.7MB) and a much faster load time (require("./ripple-latest.js") 267ms vs 337ms).

Also removed "babel-runtime" dependency (no longer used) & some outdated comments.

[intelliot]

Great catch. Thanks!