[inspector] Make InspectorTest.sendCommand* private

test/inspector/runtime/evaluate-async-with-wrap-error.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.
 
 print("Test that Runtime.evaluate correctly process errors during wrapping \
 async result.");
 
 var evaluateArguments = {
   expression: "Promise.resolve(Symbol(123))",
   returnByValue: true,
   awaitPromise: true
 };
-InspectorTest.sendCommandPromise("Runtime.evaluate", evaluateArguments)
+Protocol.Runtime.evaluate(evaluateArguments)
   .then(message => InspectorTest.logMessage(message))
   .then(_ => InspectorTest.completeTest());