Make large string use large object space.

Bug: 21209641

(cherry-picked from commit 38fafa18f0fcf610f6314a0fc4165e04e6e5d017)

Change-Id: If6d708307ba1ecdde6bf856d31dceac9ee782fb7
diff --git a/runtime/mirror/string-inl.h b/runtime/mirror/string-inl.h
index 8d9c08d..b689057 100644
--- a/runtime/mirror/string-inl.h
+++ b/runtime/mirror/string-inl.h
@@ -162,8 +162,8 @@
   }
   gc::Heap* heap = Runtime::Current()->GetHeap();
   return down_cast<String*>(
-      heap->AllocObjectWithAllocator<kIsInstrumented, false>(self, string_class, size,
-                                                             allocator_type, pre_fence_visitor));
+      heap->AllocObjectWithAllocator<kIsInstrumented, true>(self, string_class, size,
+                                                            allocator_type, pre_fence_visitor));
 }
 
 template <bool kIsInstrumented>