[debug] remove debug command processor from regress tests.

test/mjsunit/regress/regress-1639.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 13 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --expose-debug-as debug
 // Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 var breaks = 0;
 var exception = false;
 
-function sendCommand(state, cmd) {
-  // Get the debug command processor in paused state.
-  var dcp = state.debugCommandProcessor(false);
-  var request = JSON.stringify(cmd);
-  var response = dcp.processDebugJSONRequest(request);
-}
-
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
       var line = event_data.sourceLineText();
       print('break: ' + line);
 
       assertEquals(-1, line.indexOf('NOBREAK'),
                    "should not break on unexpected lines")
       assertEquals('BREAK ' + breaks, line.substr(-7));
       breaks++;
-      if (breaks < 4) {
-        sendCommand(exec_state, {
-          seq: 0,
-          type: "request",
-          command: "continue",
-          arguments: { stepaction: "next" }
-        });
-      }
+      if (breaks < 4) exec_state.prepareStep(Debug.StepAction.StepNext);
     }
   } catch (e) {
     print(e);
     exception = true;
   }
 }
 
 // Add the debug event listener.
 Debug.setListener(listener);
 
@@ skipping 13 matching lines @@
 function c() {
   a();
 }
 
 // Set a break point and call to invoke the debug event listener.
 Debug.setBreakPoint(b, 0, 0);
 a(b);
 a(); // BREAK 3
 
 assertFalse(exception);