[debug-wrapper] migrate debug-backtrace from DCP.

test/debugger/test-api.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.
 
 "use strict";
 
 // If true, prints all messages sent and received by inspector.
 const printProtocolMessages = false;
 
 // The active wrapper instance.
@@ skipping 296 matching lines @@
     const id = this.getNextMessageId();
     const msg = JSON.stringify({
       id: id,
       method: method,
       params: params,
     });
     return { msgid : id, msg: msg };
   }
 
   receiveMessage(message) {
-    if (printProtocolMessages) print(message);
-
     const parsedMessage = JSON.parse(message);
+    if (printProtocolMessages) {
+      print(JSON.stringify(parsedMessage, undefined, 1));
+    }
     if (parsedMessage.id !== undefined) {
       this.receivedMessages.set(parsedMessage.id, parsedMessage);
     }
 
     this.dispatchMessage(parsedMessage);
   }
 
   sendMessage(message) {
     if (printProtocolMessages) print(message);
     send(message);
@@ skipping 270 matching lines @@
     this.sendMessage(msg);
     this.takeReplyChecked(msgid);
   }
 
   execStateFrame(frame) {
     const scriptid = parseInt(frame.location.scriptId);
     const line = frame.location.lineNumber;
     const column = frame.location.columnNumber;
     const loc = %ScriptLocationFromLine2(scriptid, line, column, 0);
     const func = { name : () => frame.functionName };
+    const index = JSON.parse(frame.callFrameId).ordinal;
 
     function allScopes() {
       const scopes = [];
       for (let i = 0; i < frame.scopeChain.length; i++) {
         scopes.push(this.execStateScope(frame, i));
       }
       return scopes;
     };
 
     return { sourceColumn : () => loc.column,
              sourceLine : () => loc.line + 1,
              sourceLineText : () => loc.sourceText,
              evaluate : (expr) => this.evaluateOnCallFrame(frame, expr),
              functionName : () => frame.functionName,
              func : () => func,
+             index : () => index,
              localCount : () => this.execStateFrameLocalCount(frame),
              localName : (ix) => this.execStateFrameLocalName(frame, ix),
              localValue: (ix) => this.execStateFrameLocalValue(frame, ix),
              receiver : () => this.evaluateOnCallFrame(frame, "this"),
              restart : () => this.execStateFrameRestart(frame),
              scopeCount : () => frame.scopeChain.length,
              scope : (index) => this.execStateScope(frame, index),
              allScopes : allScopes.bind(this)
            };
   }
@@ skipping 129 matching lines @@
     debug.instance = new DebugWrapper();
     debug.instance.enable();
   }
   return debug.instance;
 }});
 
 Object.defineProperty(debug, 'ScopeType', { get: function() {
   const instance = debug.Debug;
   return instance.ScopeType;
 }});