Fix canonicalization of --url_mapping URIs in gen_snapshot

runtime/bin/dartutils.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 BIN_DARTUTILS_H_
 #define BIN_DARTUTILS_H_
 
 #include "bin/isolate_data.h"
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
@@ skipping 181 matching lines @@
     return isolate_data->builtin_lib();
   }
 
   static bool SetOriginalWorkingDirectory();
 
   static const char* MapLibraryUrl(CommandLineOptions* url_mapping,
                                    const char* url_string);
 
   static Dart_Handle ResolveUriInWorkingDirectory(Dart_Handle script_uri);
   static Dart_Handle FilePathFromUri(Dart_Handle script_uri);
+  static Dart_Handle ResolveUri(Dart_Handle library_url, Dart_Handle url);
 
   // Sniffs the specified text_buffer to see if it contains the magic number
   // representing a script snapshot. If the text_buffer is a script snapshot
   // the return value is an updated pointer to the text_buffer pointing past
   // the magic number value. The 'buffer_len' parameter is also appropriately
   // adjusted.
   static const uint8_t* SniffForMagicNumber(const uint8_t* text_buffer,
                                             intptr_t* buffer_len,
                                             bool* is_snapshot);
 
@@ skipping 450 matching lines @@
   bool is_typed_data_;
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(ScopedMemBuffer);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_DARTUTILS_H_