[snapshot] support including templates in the snapshot.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index c5a31791d7f5c8459d9d681124b929b290d36244..a990ccd61de69a70698f20b47f7bc9253c0aa892 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -2895,6 +2895,8 @@ void Heap::CreateInitialObjects() {
       handle(Smi::FromInt(Isolate::kArrayProtectorValid), isolate()));
   set_species_protector(*species_cell);
 
+  set_serialized_templates(empty_fixed_array());
+
   set_weak_stack_trace_list(Smi::FromInt(0));
 
   set_noscript_shared_function_infos(Smi::FromInt(0));
@@ -2932,6 +2934,7 @@ bool Heap::RootCanBeWrittenAfterInitialization(Heap::RootListIndex root_index) {
     case kRetainedMapsRootIndex:
     case kNoScriptSharedFunctionInfosRootIndex:
     case kWeakStackTraceListRootIndex:
+    case kSerializedTemplatesRootIndex:
 // Smi values
 #define SMI_ENTRY(type, name, Name) case k##Name##RootIndex:
       SMI_ROOT_LIST(SMI_ENTRY)