Make snapshot.h usable without objects-inl.h header.

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/snapshot/snapshot.h"
 
 #include "src/api.h"
 #include "src/base/platform/platform.h"
 #include "src/full-codegen/full-codegen.h"
 
 namespace v8 {
 namespace internal {
 
 #ifdef DEBUG
 bool Snapshot::SnapshotIsValid(v8::StartupData* snapshot_blob) {
   return !Snapshot::ExtractStartupData(snapshot_blob).is_empty() &&
          !Snapshot::ExtractContextData(snapshot_blob).is_empty();
 }
 #endif  // DEBUG
 
 
+bool Snapshot::HaveASnapshotToStartFrom(Isolate* isolate) {
+  // Do not use snapshots if the isolate is used to create snapshots.
+  return isolate->snapshot_blob() != NULL &&
+         isolate->snapshot_blob()->data != NULL;
+}
+
+
 bool Snapshot::EmbedsScript(Isolate* isolate) {
   if (!isolate->snapshot_available()) return false;
   return ExtractMetadata(isolate->snapshot_blob()).embeds_script();
 }
 
 
 uint32_t Snapshot::SizeOfFirstPage(Isolate* isolate, AllocationSpace space) {
   DCHECK(space >= FIRST_PAGED_SPACE && space <= LAST_PAGED_SPACE);
   if (!isolate->snapshot_available()) {
     return static_cast<uint32_t>(MemoryAllocator::PageAreaSize(space));
@@ skipping 187 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