Remove stale webpack config that injects superGet.

This was used with mobx4 to replace babel's getter with a mobx aware
version. With mobx6, we no longer require this.

Author: na9da

buildprocess/webpack.config.js

@@ -35,18 +35,6 @@ module.exports = function (devMode, hot) {
             path.resolve(__dirname, "..", "lib")
           ],
           use: [
-            {
-              // Replace Babel's super.property getter with one that is MobX aware.
-              loader: require.resolve("string-replace-loader"),
-              options: {
-                // getter code generated by babel-core ^7.16.0
-                search:
-                  "function _get\\(\\).*?return _get\\.apply\\(this, arguments\\).*",
-                replace:
-                  "var _get = require('terriajs/lib/Core/superGet').default;",
-                flags: "g"
-              }
-            },
             {
               loader: "babel-loader",
               options: {