Added command line debugger to D8 shell....

src/debug-delay.js

Index: src/debug-delay.js
===================================================================
--- src/debug-delay.js	(revision 993)
+++ src/debug-delay.js	(working copy)
@@ -1329,6 +1329,9 @@
 
   // Clear break point.
   Debug.clearBreakPoint(break_point);
+
+  // Add the cleared break point number to the response.
+  response.body = { breakpoint: break_point }
 }
 
 
@@ -1388,6 +1391,11 @@
 
 
 DebugCommandProcessor.prototype.frameRequest_ = function(request, response) {
+  // No frames no source.
+  if (this.exec_state_.frameCount() == 0) {
+    return response.failed('No frames');
+  }
+
   // With no arguments just keep the selected frame.
   if (request.arguments && request.arguments.number >= 0) {
     this.exec_state_.setSelectedFrame(request.arguments.number);
@@ -1453,6 +1461,11 @@
 
 
 DebugCommandProcessor.prototype.sourceRequest_ = function(request, response) {
+  // No frames no source.
+  if (this.exec_state_.frameCount() == 0) {
+    return response.failed('No source');
+  }
+
   var from_line;
   var to_line;
   var frame = this.exec_state_.frame();