Use a single file for app snapshots.

runtime/bin/gen_snapshot.cc

 // 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.
 
 // Generate a snapshot file after loading all the scripts specified on the
 // command line.
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 1036 matching lines @@
   uint8_t* rodata_blob_buffer = NULL;
   intptr_t rodata_blob_size = 0;
 
   // Precompile with specified embedder entry points
   result = Dart_Precompile(standalone_entry_points, true);
   CHECK_RESULT(result);
 
   // Create a precompiled snapshot.
   bool as_assembly = assembly_filename != NULL;
   if (as_assembly) {
-    result = Dart_CreatePrecompiledSnapshotAssembly(&vm_isolate_buffer,
-                                                    &vm_isolate_size,
-                                                    &isolate_buffer,
-                                                    &isolate_size,
-                                                    &assembly_buffer,
+    result = Dart_CreatePrecompiledSnapshotAssembly(&assembly_buffer,
                                                     &assembly_size);
     CHECK_RESULT(result);
   } else {
     result = Dart_CreatePrecompiledSnapshotBlob(&vm_isolate_buffer,
                                                 &vm_isolate_size,
                                                 &isolate_buffer,
                                                 &isolate_size,
                                                 &instructions_blob_buffer,
                                                 &instructions_blob_size,
                                                 &rodata_blob_buffer,
@@ skipping 282 matching lines @@
   EventHandler::Stop();
   return 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   return dart::bin::main(argc, argv);
 }