Decrease download size by removing promise polyfill

package.json

@@ -45,8 +45,7 @@
     "d3-request": "^1.0.6",
     "d3-scale": "^1.0.6",
     "d3-selection": "^1.1.0",
-    "d3.promise": "^2.0.0",
-    "es6-promise": "^4.1.1"
+    "d3.promise": "^2.0.0"
   },
   "devDependencies": {
     "babel-core": "^6.26.0",

src/js/init.js

@@ -4,7 +4,6 @@
 
 import * as d3request from 'd3-request';
 import * as d3selection from 'd3-selection';
-import {Promise} from 'es6-promise';
 
 import {Ploidy} from './ploidy';
 import {Layout} from './layouts/layout';

src/js/lib.js

@@ -7,42 +7,6 @@ import * as d3selection from 'd3-selection';
 import {ModelAdapter} from './model-adapter';
 import {Chromosome} from './views/chromosome';
 
-/**
- * Polyfill for Object.assign, to enable usage in IE 10.
- *
- * This is a lightly modified version of
- * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#Polyfill
- */
-if (typeof Object.assign !== 'function') {
-  // Must be writable: true, enumerable: false, configurable: true
-  Object.defineProperty(Object, "assign", {
-    value: function assign(target, varArgs) { // .length of function is 2
-      'use strict';
-      if (target === null) { // TypeError if undefined or null
-        throw new TypeError('Cannot convert undefined or null to object');
-      }
-
-      var to = Object(target);
-
-      for (var index = 1; index < arguments.length; index++) {
-        var nextSource = arguments[index];
-
-        if (nextSource !== null) { // Skip over if undefined or null
-          for (var nextKey in nextSource) {
-            // Avoid bugs when hasOwnProperty is shadowed
-            if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
-              to[nextKey] = nextSource[nextKey];
-            }
-          }
-        }
-      }
-      return to;
-    },
-    writable: true,
-    configurable: true
-  });
-}
-
 var d3 = Object.assign({}, d3selection);
 
 /**

src/js/services.js

@@ -1,7 +1,6 @@
 import * as d3request from 'd3-request';
 import * as d3dispatch from 'd3-dispatch';
 import * as d3promise from 'd3.promise';
-import {Promise} from 'es6-promise';
 
 import {Object} from './lib.js';
 

yarn.lock

@@ -1897,10 +1897,6 @@ es6-map@^0.1.3:
     es6-symbol "~3.1.1"
     event-emitter "~0.3.5"
 
-es6-promise@^4.1.1:
-  version "4.2.4"
-  resolved "https://registry.yarnpkg.com/es6-promise/-/es6-promise-4.2.4.tgz#dc4221c2b16518760bd8c39a52d8f356fc00ed29"
-
 es6-set@~0.1.5:
   version "0.1.5"
   resolved "https://registry.yarnpkg.com/es6-set/-/es6-set-0.1.5.tgz#d2b3ec5d4d800ced818db538d28974db0a73ccb1"