Use a single file for app snapshots.

runtime/include/dart_api.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 INCLUDE_DART_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
@@ skipping 3097 matching lines @@
  *  The vm isolate snapshot, kInstructionsSnapshot and kDataSnapshot should be
  *  passed as arguments to Dart_Initialize. The isolate snapshot should be
  *  passed to Dart_CreateIsolate.
  *
  *  The buffers are scope allocated and are only valid until the next call to
  *  Dart_ExitScope.
  *
  * \return A valid handle if no error occurs during the operation.
  */
 DART_EXPORT Dart_Handle Dart_CreatePrecompiledSnapshotAssembly(
-    uint8_t** vm_isolate_snapshot_buffer,
-    intptr_t* vm_isolate_snapshot_size,
-    uint8_t** isolate_snapshot_buffer,
-    intptr_t* isolate_snapshot_size,
     uint8_t** assembly_buffer,
     intptr_t* assembly_size);
 
 
 /**
  *  Same as Dart_CreatePrecompiledSnapshotAssembly, except the instruction and
  *  data snapshot pieces are provided directly as bytes that the embedder can
  *  load with mmap. The instructions piece must be loaded with read and
  *  execute permissions; the rodata piece may be loaded as read-only.
  */
@@ skipping 56 matching lines @@
 /**
  *  Returns whether the VM was initialized with a precompiled snapshot. Only
  *  valid after Dart_Initialize.
  *  DEPRECATED. This is currently used to disable Platform.executable and
  *  Platform.resolvedExecutable under precompilation to prevent process
  *  spawning tests from becoming fork-bombs.
  */
 DART_EXPORT bool Dart_IsRunningPrecompiledCode();
 
 #endif  /* INCLUDE_DART_API_H_ */  /* NOLINT */