[inspector] Refactor protocol-test.js

test/inspector/runtime/get-properties-preview.js

 // Copyright 2016 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.
 
-InspectorTest.setupInjectedScriptEnvironment();
+let {session, contextGroup, Protocol} = InspectorTest.start('Tests generated previews in Runtime.getProperties');
+
+contextGroup.setupInjectedScriptEnvironment();
 
 Protocol.Runtime.evaluate({ "expression": "({p1: {a:1}, p2: {b:'foo', bb:'bar'}})" }).then(callbackEvaluate);
 
 function callbackEvaluate(result)
 {
   Protocol.Runtime.getProperties({ "objectId": result.result.result.objectId, "ownProperties": true }).then(callbackGetProperties.bind(null, false));
   Protocol.Runtime.getProperties({ "objectId": result.result.result.objectId, "ownProperties": true, "generatePreview": true }).then(callbackGetProperties.bind(null, true));
 }
 
 function callbackGetProperties(completeTest, result)
 {
   for (var property of result.result.result) {
     if (!property.value || property.name === "__proto__")
       continue;
     if (property.value.preview)
       InspectorTest.log(property.name + " : " + JSON.stringify(property.value.preview, null, 4));
     else
       InspectorTest.log(property.name + " : " + property.value.description);
   }
   if (completeTest)
     InspectorTest.completeTest();
 }