Only reload libraries when they may have been modified.

runtime/bin/loader.h

 // Copyright (c) 2016, 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 BIN_LOADER_H_
 #define BIN_LOADER_H_
 
 #include "bin/isolate_data.h"
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
@@ skipping 43 matching lines @@
   // Must be accessed with monitor_ held.
   intptr_t pending_operations_;
 
   // The result of an I/O request to the service isolate. Payload is either
   // a UInt8Array or a C string containing an error message.
   struct IOResult {
     uint8_t* payload;
     intptr_t payload_length;
     char* library_uri;
     char* uri;
+    char* resolved_uri;
     int8_t tag;
 
     void Setup(Dart_CObject* message);
     void Cleanup();
   };
   // An array of I/O results queued from the service isolate.
   IOResult* results_;
   intptr_t results_length_;
   intptr_t results_capacity_;
   uint8_t* payload_;
@@ skipping 65 matching lines @@
 
   // This is the global callback for the native message handlers.
   static void NativeMessageHandler(Dart_Port dest_port_id,
                                    Dart_CObject* message);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_LOADER_H_