rdf-canonize throws SyntaxError in IE due to untranspiled sources for the browser

[AlexeyMz]

browser property in package.json has the following value:

...
"./index.js": "./dist/index.js",

Which causes untranspiled library sources (with async-functions and class declarations) to be included when rdf-canonize is used as a dependency, e.g. when importing jsonld.

This was discovered here: digitalbazaar/jsonld.js#319

[AlexeyMz]

For JSON-LD this PR fixes Webpack configuration to bundle pre-transpiled rdf-canonize package:
digitalbazaar/jsonld.js#321

So in case anyone wants to use ES5-compatible JSON-LD bundle it should be enough to import jsonld/dist/jsonld.js instead of main entry point.