Add script context with context-allocated "const this"

src/snapshot/snapshot-common.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The common functionality when building with or without snapshots.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/base/platform/platform.h"
@@ skipping 59 matching lines @@
   Vector<const byte> context_data = ExtractContextData(blob);
   SnapshotData snapshot_data(context_data);
   Deserializer deserializer(&snapshot_data);
 
   MaybeHandle<Object> maybe_context = deserializer.DeserializePartial(
       isolate, global_proxy, outdated_contexts_out);
   Handle<Object> result;
   if (!maybe_context.ToHandle(&result)) return MaybeHandle<Context>();
   CHECK(result->IsContext());
   // If the snapshot does not contain a custom script, we need to update
-  // the global object for exactly one context.
-  CHECK(EmbedsScript(isolate) || (*outdated_contexts_out)->length() == 1);
+  // the global object for exactly two contexts: the builtins context and the
+  // script context that has the global "this" binding.
+  CHECK(EmbedsScript(isolate) || (*outdated_contexts_out)->length() == 2);
   if (FLAG_profile_deserialization) {
     double ms = timer.Elapsed().InMillisecondsF();
     int bytes = context_data.length();
     PrintF("[Deserializing context (%d bytes) took %0.3f ms]\n", bytes, ms);
   }
   return Handle<Context>::cast(result);
 }
 
 
 void CalculateFirstPageSizes(bool is_default_snapshot,
@@ skipping 129 matching lines @@
   memcpy(&startup_length, data->data + kStartupLengthOffset, kIntSize);
   int context_offset = ContextOffset(startup_length);
   const byte* context_data =
       reinterpret_cast<const byte*>(data->data + context_offset);
   DCHECK_LT(context_offset, data->raw_size);
   int context_length = data->raw_size - context_offset;
   return Vector<const byte>(context_data, context_length);
 }
 }  // namespace internal
 }  // namespace v8