[heap,snapshot] Replace first page size from snapshots with page trimming

src/heap/heap.cc

 // Copyright 2012 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/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/context-slot-cache.h"
 #include "src/base/bits.h"
@@ skipping 5444 matching lines @@
   roots_[kRealStackLimitRootIndex] = Smi::FromInt(0);
 }
 
 void Heap::PrintAlloctionsHash() {
   uint32_t hash = StringHasher::GetHashCore(raw_allocations_hash_);
   PrintF("\n### Allocations = %u, hash = 0x%08x\n", allocations_count(), hash);
 }
 
 
 void Heap::NotifyDeserializationComplete() {
-  deserialization_complete_ = true;
-#ifdef DEBUG
-  // All pages right after bootstrapping must be marked as never-evacuate.
+  DCHECK_EQ(0, gc_count());
   PagedSpaces spaces(this);
   for (PagedSpace* s = spaces.next(); s != NULL; s = spaces.next()) {
+    if (isolate()->snapshot_available()) s->ShrinkImmortalImmovablePages();
+#ifdef DEBUG
+    // All pages right after bootstrapping must be marked as never-evacuate.
     for (Page* p : *s) {
       CHECK(p->NeverEvacuate());
     }
+#endif  // DEBUG
   }
-#endif  // DEBUG
+
+  deserialization_complete_ = true;
 }
 
 void Heap::SetEmbedderHeapTracer(EmbedderHeapTracer* tracer) {
   mark_compact_collector()->SetEmbedderHeapTracer(tracer);
 }
 
 bool Heap::UsingEmbedderHeapTracer() {
   return mark_compact_collector()->UsingEmbedderHeapTracer();
 }
 
@@ skipping 967 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8