Added /build/three.es2015.js target for "jsnext:main" (#9597)

* Added /build/three.es2015.js target for jsnext:main

* Generated "three.es2015.js" using `npm run build`

* Renamed "three.es2015.js" to "three.jsnext.js"

* Renamed "three.jsnext.js" to "three.next.js"

* Fixed path to the es bundle

* ES Module bundle is now /build/three.modules.js

package.json

@@ -3,12 +3,14 @@
   "version": "0.81.2",
   "description": "JavaScript 3D library",
   "main": "build/three.js",
+  "jsnext:main": "build/three.modules.js",
   "files": [
     "package.json",
     "LICENSE",
     "README.md",
     "build/three.js",
     "build/three.min.js",
+    "build/three.modules.js",
     "src",
     "examples/js",
     "examples/fonts",
@@ -45,7 +47,7 @@
   "devDependencies": {
     "argparse": "^1.0.3",
     "jscs": "^1.13.1",
-    "rollup": "^0.34.8",
+    "rollup": "^0.36.3",
     "rollup-watch": "^2.5.0",
     "uglify-js": "^2.6.0"
   }

rollup.config.js

@@ -1,4 +1,3 @@
-import * as fs from 'fs';
 
 var outro = `
 Object.defineProperty( exports, 'AudioContext', {
@@ -28,11 +27,19 @@ function glsl () {
 
 export default {
 	entry: 'src/Three.js',
-	dest: 'build/three.js',
-	moduleName: 'THREE',
-	format: 'umd',
 	plugins: [
 		glsl()
 	],
+	targets: [
+		{
+			format: 'umd',
+			moduleName: 'THREE',
+			dest: 'build/three.js'
+		},
+		{
+			format: 'es',
+			dest: 'build/three.modules.js'
+		}
+	],
 	outro: outro
 };