Remove unwanted copyToVector() uses.

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 8da90c1d1f2c9f6a4735dac439f5f8165d4cc7b0..362458bc569d665a8d1d51e4981909b4871e898c 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -2116,10 +2116,8 @@ void Document::updateUseShadowTreesIfNeeded()
     if (m_useElementsNeedingUpdate.isEmpty())
         return;
 
-    HeapVector<Member<SVGUseElement>> elements;
-    copyToVector(m_useElementsNeedingUpdate, elements);
-    m_useElementsNeedingUpdate.clear();
-
+    HeapHashSet<Member<SVGUseElement>> elements;
+    m_useElementsNeedingUpdate.swap(elements);
     for (SVGUseElement* element : elements)
         element->buildPendingResource();
 }