Store embed-script flag as metadata into snapshot blob.

src/bootstrapper.cc

 // Copyright 2014 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.
 
 #include "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
 #include "src/extensions/free-buffer-extension.h"
@@ skipping 2560 matching lines @@
     isolate()->clear_pending_exception();
     return false;
   }
   TransferObject(obj, object);
   return true;
 }
 
 
 void Genesis::TransferNamedProperties(Handle<JSObject> from,
                                       Handle<JSObject> to) {
+  // If JSObject::AddProperty asserts due to already existing property,
+  // it is likely due to both global objects sharing property name(s).
+  // Merging those two global objects is impossible.
+  // The global template must not create properties that already exist
+  // in the snapshotted global object.
   if (from->HasFastProperties()) {
     Handle<DescriptorArray> descs =
         Handle<DescriptorArray>(from->map()->instance_descriptors());
     for (int i = 0; i < from->map()->NumberOfOwnDescriptors(); i++) {
       PropertyDetails details = descs->GetDetails(i);
       switch (details.type()) {
         case FIELD: {
           HandleScope inner(isolate());
           Handle<Name> key = Handle<Name>(descs->GetKey(i));
           FieldIndex index = FieldIndex::ForDescriptor(from->map(), i);
@@ skipping 260 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 } }  // namespace v8::internal