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

spec/api-remote-spec.js

@@ -237,6 +237,16 @@ describe('remote module', () => {
     const print = path.join(fixtures, 'module', 'print_name.js')
     const printName = remote.require(print)
 
+    it('converts NaN to undefined', () => {
+      assert.strictEqual(printName.getNaN(), undefined)
+      assert.strictEqual(printName.echo(NaN), undefined)
+    })
+
+    it('converts Infinity to undefined', () => {
+      assert.strictEqual(printName.getInfinity(), undefined)
+      assert.strictEqual(printName.echo(Infinity), undefined)
+    })
+
     it('keeps its constructor name for objects', () => {
       const buf = Buffer.from('test')
       assert.equal(printName.print(buf), 'Buffer')