Support breakpoints in deferred libraries

tests/standalone/debugger/debug_lib.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Library used by debugger wire protocol tests (standalone VM debugging).
 
 library DartDebugger;
 
 import "dart:async";
 import "dart:convert";
@@ skipping 379 matching lines @@
 }
 
 
 Resume() => new RunCommand.resume();
 Step() => new RunCommand.step();
 StepInto() => new RunCommand.stepInto();
 StepOut() => new RunCommand.stepOut();
 
 class SetBreakpointCommand extends Command {
   int line;
-  SetBreakpointCommand(int this.line) {
+  String url;
+  SetBreakpointCommand(this.line, this.url) {
     template = {"id": 0,
                 "command": "setBreakpoint",
                 "params": { "isolateId": 0,
                             "url": null,
                             "line": null }};
   }
 
   void send(Debugger debugger) {
     assert(debugger.scriptUrl != null);
-    template["params"]["url"] = debugger.scriptUrl;
+    if (url == null) {
+      url = debugger.scriptUrl;
+    }
+    template["params"]["url"] = url;
     template["params"]["line"] = line;
     debugger.sendMessage(template);
   }
 
   void matchResponse(Debugger debugger) {
     super.matchResponse(debugger);
-    print("Set breakpoint at line $line");
+    print("Set breakpoint at line $line in $url");
   }
 }
 
-SetBreakpoint(int line) => new SetBreakpointCommand(line);
+SetBreakpoint(int line, {String url}) => new SetBreakpointCommand(line, url);
 
 class Event {
   String name;
   Map params;
 
   Event(Map json) {
     name = json['event'];
     params = json['params'];
   }
 }
@@ skipping 267 matching lines @@
   targetOpts.add("--debuggee");
   print('args: ${targetOpts.join(" ")}');
 
   Process.start(Platform.executable, targetOpts).then((Process process) {
     print("Debug target process started, pid ${process.pid}.");
     process.stdin.close();
     var debugger = new Debugger(process, new DebugScript(script));
   });
   return true;
 }