perf: don't use JSON to send the result of ipcRenderer.sendSync. (#8953)

* Don't use JSON to send the result of `ipcRenderer.sendSync`.

- Change the return type of AtomViewHostMsg_Message_Sync from `base::string16`
  to `base::ListValue`
- Adjust lib/browser/api/web-contents.js and /lib/renderer/api/ipc-renderer.js
  to wrap/unwrap return values to/from array, instead of
  serializing/deserializing JSON.

This change can greatly improve `ipcRenderer.sendSync` calls where the return
value contains Buffer instances, because those are converted to Array before
being serialized to JSON(which has no efficient way of representing byte
arrays).

A simple benchmark where remote.require('fs') was used to read a 16mb file got
at least 5x faster, not to mention it used a lot less memory.  This difference
tends increases with larger buffers.

* Don't base64 encode Buffers

* Don't allocate V8ValueConverter on the heap

* Replace hidden global.sandbox with NodeBindings::IsInitialized()

* Refactoring: check NodeBindings::IsInitialized() in V8ValueConverter

* Refactor problematic test to make it more reliable

* Add tests for NaN and Infinity

atom/common/api/api_messages.h

@@ -31,7 +31,7 @@ IPC_MESSAGE_ROUTED2(AtomFrameHostMsg_Message,
 IPC_SYNC_MESSAGE_ROUTED2_1(AtomFrameHostMsg_Message_Sync,
                            base::string16 /* channel */,
                            base::ListValue /* arguments */,
-                           base::string16 /* result (in JSON) */)
+                           base::ListValue /* result */)
 
 IPC_MESSAGE_ROUTED3(AtomFrameMsg_Message,
                     bool /* send_to_all */,