Configurable vector capacity in blink::DistributedNodes

Source/core/dom/shadow/DistributedNodes.h

Index: Source/core/dom/shadow/DistributedNodes.h
diff --git a/Source/core/dom/shadow/DistributedNodes.h b/Source/core/dom/shadow/DistributedNodes.h
index 4259c7e4503724915c6a01744feef01881fd2efc..1601ad8a35ad5a896a4f46c6e6ac83bb8a410cdc 100644
--- a/Source/core/dom/shadow/DistributedNodes.h
+++ b/Source/core/dom/shadow/DistributedNodes.h
@@ -41,6 +41,7 @@ class DistributedNodes final {
     DISALLOW_ALLOCATION();
 public:
     DistributedNodes() { m_nodes.reserveInitialCapacity(32); }
+    explicit DistributedNodes(size_t capacity) { m_nodes.reserveInitialCapacity(capacity); }
 
     PassRefPtrWillBeRawPtr<Node> first() const { return m_nodes.first(); }
     PassRefPtrWillBeRawPtr<Node> last() const { return m_nodes.last(); }