[test/inspector] remove any usage of v8::Extension

test/inspector/debugger/stepping-and-break-program-api.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.
 
 InspectorTest.log('Checks that stepping is cleared after breakProgram.');
 
 InspectorTest.addScript(`
 function callBreakProgram() {
   debugger;
-  breakProgram('reason', '');
+  inspector.breakProgram('reason', '');
 }`);
 
 InspectorTest.setupScriptMap();
 (async function test() {
   Protocol.Debugger.enable();
   Protocol.Runtime.evaluate({expression: 'callBreakProgram();'});
   // Should break at this debugger statement, not at end of callBreakProgram.
   Protocol.Runtime.evaluate({expression: 'setTimeout(\'debugger;\', 0);'});
   await waitPauseAndDumpLocation();
   Protocol.Debugger.stepOver();
   await waitPauseAndDumpLocation();
   Protocol.Debugger.stepOver();
   await waitPauseAndDumpLocation();
   Protocol.Debugger.resume();
   await waitPauseAndDumpLocation();
   InspectorTest.completeTest();
 })();
 
 async function waitPauseAndDumpLocation() {
   var message = await Protocol.Debugger.oncePaused();
   InspectorTest.log('paused at:');
   InspectorTest.logSourceLocation(message.params.callFrames[0].location);
   return message;
 }