Fix Initialize & Dispose for external snapshot.

src/natives-external.cc

Index: src/natives-external.cc
diff --git a/src/natives-external.cc b/src/natives-external.cc
index 109f9c5f47bfe14cf25a69365502ac1ef7993df7..437addc213ddbd5a34524f4b0c185d987afefd74 100644
--- a/src/natives-external.cc
+++ b/src/natives-external.cc
@@ -132,9 +132,10 @@ class NativesHolder {
     DCHECK(store);
     holder_ = store;
   }
+  static bool empty() { return holder_ == NULL; }
   static void Dispose() {
-    DCHECK(holder_);
     delete holder_;
+    holder_ = NULL;
   }
 
  private:
@@ -145,19 +146,36 @@ template<NativeType type>
 NativesStore* NativesHolder<type>::holder_ = NULL;
 
 
+// The natives blob. Memory is owned by caller.
+static StartupData* natives_blob_ = NULL;
+
+
+/**
+ * Read the Natives blob, as previously set by SetNativesFromFile.
+ */
+void ReadNatives() {
+  if (natives_blob_ && NativesHolder<CORE>::empty()) {
+    SnapshotByteSource bytes(natives_blob_->data, natives_blob_->raw_size);
+    NativesHolder<CORE>::set(NativesStore::MakeFromScriptsSource(&bytes));
+    NativesHolder<EXPERIMENTAL>::set(
+        NativesStore::MakeFromScriptsSource(&bytes));
+    DCHECK(!bytes.HasMore());
+  }
+}
+
+
 /**
- * Read the Natives (library sources) blob, as generated by js2c + the build
+ * Set the Natives (library sources) blob, as generated by js2c + the build
  * system.
  */
 void SetNativesFromFile(StartupData* natives_blob) {
+  DCHECK(!natives_blob_);
   DCHECK(natives_blob);
   DCHECK(natives_blob->data);
   DCHECK(natives_blob->raw_size > 0);
 
-  SnapshotByteSource bytes(natives_blob->data, natives_blob->raw_size);
-  NativesHolder<CORE>::set(NativesStore::MakeFromScriptsSource(&bytes));
-  NativesHolder<EXPERIMENTAL>::set(NativesStore::MakeFromScriptsSource(&bytes));
-  DCHECK(!bytes.HasMore());
+  natives_blob_ = natives_blob;
+  ReadNatives();
 }