Make String16 consturctors non-inline to save binary size (150kb)

test/js-perf-test/Inspector/run.js

 // Copyright 2017 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 load('../base.js');
 
 load('debugger.js');
+load('runtime.js');
 
-var success = true;
+let success = true;
+let lastId = 0;
+let prevMessage = null;
 
 function PrintResult(name, result) {
   print(name + '-Inspector(Score): ' + result);
 }
 
 function PrintStep(name) {}
 
 function PrintError(name, error) {
   PrintResult(name, error);
   success = false;
 }
 
 
 BenchmarkSuite.config.doWarmup = undefined;
 BenchmarkSuite.config.doDeterministic = undefined;
 
 BenchmarkSuite.RunSuites({ NotifyResult: PrintResult,
                            NotifyError: PrintError,
                            NotifyStep: PrintStep });
+
+function receive(message) {
+  prevMessage = JSON.parse(message);
+}
+
+function SendMessage(method, params) {
+  let obj = {id: ++lastId, method: method};
+  if (params) {
+    obj.params = params;
+  }
+  send(JSON.stringify(obj));
+  if (prevMessage && prevMessage.id == lastId) {
+    return prevMessage;
+  }
+  return null;
+}