Revert to Babel 5 for now.

packages/xen-api/.babelrc

@@ -1,11 +1,11 @@
 {
   "comments": false,
   "compact": true,
-  "plugins": [
-    "transform-runtime"
-  ],
-  "presets": [
-    "stage-0",
-    "es2015"
+  "optional": [
+    "es7.asyncFunctions",
+    "es7.decorators",
+    "es7.exportExtensions",
+    "es7.functionBind",
+    "runtime"
   ]
 }

packages/xen-api/package.json

@@ -30,7 +30,7 @@
     ".mocha.js"
   ],
   "dependencies": {
-    "babel-runtime": "^6",
+    "babel-runtime": "^5.8.34",
     "blocked": "^1.1.0",
     "bluebird": "^2.9.21",
     "debug": "^2.1.3",
@@ -53,12 +53,8 @@
     "xo-collection": "^0.4.0"
   },
   "devDependencies": {
-    "babel-cli": "^6.1.2",
-    "babel-core": "^6.1.2",
+    "babel": "^5.8.34",
     "babel-eslint": "^4.1.5",
-    "babel-plugin-transform-runtime": "^6.1.2",
-    "babel-preset-es2015": "^6.1.2",
-    "babel-preset-stage-0": "^6.1.2",
     "clarify": "^1.0.5",
     "dependency-check": "^2.5.1",
     "mocha": "^2.2.5",