Fix updating packages map on reload and add a regression test

runtime/bin/isolate_data.h

 // Copyright (c) 2012, 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.
 
 #ifndef RUNTIME_BIN_ISOLATE_DATA_H_
 #define RUNTIME_BIN_ISOLATE_DATA_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/globals.h"
@@ skipping 35 matching lines @@
     ASSERT(lib != NULL);
     ASSERT(!Dart_IsError(lib));
     builtin_lib_ = Dart_NewPersistentHandle(lib);
   }
 
   char* script_url;
   char* package_root;
   char* packages_file;
   uint8_t* udp_receive_buffer;
 
+  void UpdatePackagesFile(const char* packages_file_) {
+    if (packages_file != NULL) {
+      free(packages_file);
+      packages_file = NULL;
+    }
+    packages_file = strdup(packages_file_);
+  }
+
   // While loading a loader is associated with the isolate.
   bool HasLoader() const { return loader_ != NULL; }
   Loader* loader() const {
     ASSERT(loader_ != NULL);
     return loader_;
   }
   void set_loader(Loader* loader) {
     ASSERT((loader_ == NULL) || (loader == NULL));
     loader_ = loader;
   }
@@ skipping 10 matching lines @@
   AppSnapshot* app_snapshot_;
   MallocGrowableArray<char*>* dependencies_;
 
   DISALLOW_COPY_AND_ASSIGN(IsolateData);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // RUNTIME_BIN_ISOLATE_DATA_H_