Move RootIndexMap out of serializer file.

src/snapshot/serialize.cc

Index: src/snapshot/serialize.cc
diff --git a/src/snapshot/serialize.cc b/src/snapshot/serialize.cc
index 51892de3eb1a1a1f84c0f58e511c0b37440b7958..a6ca6e1946fe91b9de28253afea41dd8e03f9b0e 100644
--- a/src/snapshot/serialize.cc
+++ b/src/snapshot/serialize.cc
@@ -354,31 +354,6 @@ const char* ExternalReferenceEncoder::NameOfAddress(Isolate* isolate,
 }
 
 
-RootIndexMap::RootIndexMap(Isolate* isolate) {
-  map_ = isolate->root_index_map();
-  if (map_ != NULL) return;
-  map_ = new HashMap(HashMap::PointersMatch);
-  for (uint32_t i = 0; i < Heap::kStrongRootListLength; i++) {
-    Heap::RootListIndex root_index = static_cast<Heap::RootListIndex>(i);
-    Object* root = isolate->heap()->root(root_index);
-    // Omit root entries that can be written after initialization. They must
-    // not be referenced through the root list in the snapshot.
-    if (root->IsHeapObject() &&
-        isolate->heap()->RootCanBeTreatedAsConstant(root_index)) {
-      HeapObject* heap_object = HeapObject::cast(root);
-      HashMap::Entry* entry = LookupEntry(map_, heap_object, false);
-      if (entry != NULL) {
-        // Some are initialized to a previous value in the root list.
-        DCHECK_LT(GetValue(entry), i);
-      } else {
-        SetValue(LookupEntry(map_, heap_object, true), i);
-      }
-    }
-  }
-  isolate->set_root_index_map(map_);
-}
-
-
 class CodeAddressMap: public CodeEventLogger {
  public:
   explicit CodeAddressMap(Isolate* isolate)