Reduce transpilation on Node.js >=4 (#1068)

Better startup performance and improved stack traces.

lib/babel-config.js

@@ -4,6 +4,7 @@ var chalk = require('chalk');
 var figures = require('figures');
 var convertSourceMap = require('convert-source-map');
 var objectAssign = require('object-assign');
+var semver = require('semver');
 var colors = require('./colors');
 
 function validate(conf) {
@@ -40,9 +41,13 @@ function lazy(initFn) {
 }
 
 var defaultPresets = lazy(function () {
+	var esPreset = semver.satisfies(process.version, '>=4') ?
+		'babel-preset-es2015-node4' :
+		'babel-preset-es2015';
+
 	return [
 		require('babel-preset-stage-2'),
-		require('babel-preset-es2015')
+		require(esPreset)
 	];
 });
 

lib/caching-precompiler.js

@@ -76,7 +76,8 @@ CachingPrecompiler.prototype._transform = function (code, filePath, hash) {
 CachingPrecompiler.prototype._createTransform = function () {
 	var salt = packageHash.sync(
 		[require.resolve('../package.json')].concat(babelConfigHelper.pluginPackages),
-		JSON.stringify(this.babelConfig)
+		JSON.stringify(this.babelConfig),
+		process.version.split('.')[0]
 	);
 
 	return cachingTransform({

package.json

@@ -100,6 +100,7 @@
     "babel-plugin-espower": "^2.3.1",
     "babel-plugin-transform-runtime": "^6.15.0",
     "babel-preset-es2015": "^6.16.0",
+    "babel-preset-es2015-node4": "^2.1.0",
     "babel-preset-stage-2": "^6.17.0",
     "babel-runtime": "^6.11.6",
     "bluebird": "^3.0.0",
@@ -151,6 +152,7 @@
     "repeating": "^2.0.0",
     "require-precompiled": "^0.1.0",
     "resolve-cwd": "^1.0.0",
+    "semver": "^5.3.0",
     "set-immediate-shim": "^1.0.1",
     "source-map-support": "^0.4.0",
     "stack-utils": "^0.4.0",