Run tests through babel globally. (gatsbyjs#1780)

* Run tests through babel globally.

* Ignore tests in production environment.

* format

.babelrc

@@ -1,7 +1,12 @@
 {
   "sourceMaps": true,
-  "ignore": ["__tests__", "dist"],
   "presets": [
     "./.babelrc.js"
-  ]
+  ],
+  "ignore": ["dist"],
+  "env": {
+    "production": {
+      "ignore": ["__tests__", "dist"],
+    }
+  },
 }

.babelrc.js

@@ -2,15 +2,15 @@ const r = m => require.resolve(m)
 
 function preset(context, options = {}) {
   const { browser = false, debug = false } = options
-  const { NODE_ENV, BABEL_ENV } = process.env;
+  const { NODE_ENV, BABEL_ENV } = process.env
 
   const PRODUCTION = (BABEL_ENV || NODE_ENV) === "production"
 
   const browserConfig = {
     useBuiltIns: false,
     targets: {
       browsers: PRODUCTION
-        ? [`last 4 versions`, `safari >= 7`, 'ie >= 9']
+        ? [`last 4 versions`, `safari >= 7`, "ie >= 9"]
         : [`last 2 versions`, `not ie <= 11`, `not android 4.4.3`],
       uglify: PRODUCTION,
     },
@@ -26,16 +26,15 @@ function preset(context, options = {}) {
     presets: [
       [
         r("babel-preset-env"),
-          Object.assign({
+        Object.assign(
+          {
             loose: true,
             debug: !!debug,
             useBuiltIns: true,
             modules: "commonjs",
           },
-          browser ?
-            browserConfig :
-            nodeConfig
-        )
+          browser ? browserConfig : nodeConfig
+        ),
       ],
       r("babel-preset-react"),
       r("babel-preset-flow"),