Teach gen_snapshot how to create script snapshots if given a core snapshot to create them against.

runtime/vm/object.cc

 // 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.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 1159 matching lines @@
   Thread* thread = Thread::Current();
   Zone* zone = thread->zone();
   ASSERT(isolate == thread->isolate());
 #if !defined(DART_PRECOMPILED_RUNTIME)
   const bool is_kernel = (kernel_program != NULL);
 #endif
   NOT_IN_PRODUCT(TimelineDurationScope tds(thread, Timeline::GetIsolateStream(),
                                            "Object::Init");)
 
 #if defined(DART_NO_SNAPSHOT)
-  bool bootstrapping = true;
+  bool bootstrapping = Dart::vm_snapshot_kind() == Snapshot::kNone;
 #elif defined(DART_PRECOMPILED_RUNTIME)
   bool bootstrapping = false;
 #else
   bool bootstrapping = is_kernel;
 #endif
 
   if (bootstrapping) {
 #if !defined(DART_PRECOMPILED_RUNTIME)
     // Object::Init version when we are bootstrapping from source or from a
     // Kernel binary.
@@ skipping 21668 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart