New Client: stable (#8426)

* try to freeze content object

* deep freeze the content object, start to implement stable

* freeze at the /common level

* go back to freezing content only on the client

* use deep-frezze-strict to support phantomjs

* use own version of deepFreeze

* update comment about deepFreeze

website/client/libs/deepFreeze.js

@@ -0,0 +1,20 @@
+// Code taken from https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze
+// and adapted
+export default function deepFreeze (obj) {
+  // Retrieve the property names defined on obj
+  const propNames = Object.getOwnPropertyNames(obj);
+  const propNamesLength = propNames.length;
+
+  // Freeze properties before freezing self
+  for (let i = 0; i < propNamesLength; i++) {
+    const prop = obj[propNames[i]];
+
+    // Freeze prop if it is an object
+    if (typeof prop === 'object' && prop !== null) {
+      deepFreeze(prop);
+    }
+  }
+
+  // Freeze self (no-op if already frozen)
+  return Object.freeze(obj);
+}