Fix memory leak in natives-external.

src/natives-external.cc

Index: src/natives-external.cc
diff --git a/src/natives-external.cc b/src/natives-external.cc
index e601808fe8182055683d32133081b36e46c9938f..109f9c5f47bfe14cf25a69365502ac1ef7993df7 100644
--- a/src/natives-external.cc
+++ b/src/natives-external.cc
@@ -132,6 +132,10 @@ class NativesHolder {
     DCHECK(store);
     holder_ = store;
   }
+  static void Dispose() {
+    DCHECK(holder_);
+    delete holder_;
+  }
 
  private:
   static NativesStore* holder_;
@@ -157,6 +161,15 @@ void SetNativesFromFile(StartupData* natives_blob) {
 }
 
 
+/**
+ * Release memory allocated by SetNativesFromFile.
+ */
+void DisposeNatives() {
+  NativesHolder<CORE>::Dispose();
+  NativesHolder<EXPERIMENTAL>::Dispose();
+}
+
+
 // Implement NativesCollection<T> bsaed on NativesHolder + NativesStore.
 //
 // (The callers expect a purely static interface, since this is how the