Avoid WTF::Vector::at() and operator[] in core/html.

third_party/WebKit/Source/core/html/imports/HTMLImportTreeRoot.cpp

Index: third_party/WebKit/Source/core/html/imports/HTMLImportTreeRoot.cpp
diff --git a/third_party/WebKit/Source/core/html/imports/HTMLImportTreeRoot.cpp b/third_party/WebKit/Source/core/html/imports/HTMLImportTreeRoot.cpp
index d23db10b4e87d4744c387a341278cab934fbd4cb..47e13292e594b79b8fe457502c14c32f689ee432 100644
--- a/third_party/WebKit/Source/core/html/imports/HTMLImportTreeRoot.cpp
+++ b/third_party/WebKit/Source/core/html/imports/HTMLImportTreeRoot.cpp
@@ -25,8 +25,8 @@ HTMLImportTreeRoot::HTMLImportTreeRoot(Document* document)
 HTMLImportTreeRoot::~HTMLImportTreeRoot() {}
 
 void HTMLImportTreeRoot::dispose() {
-  for (size_t i = 0; i < m_imports.size(); ++i)
-    m_imports[i]->dispose();
+  for (const auto& importChild : m_imports)
+    importChild->dispose();
   m_imports.clear();
   m_document = nullptr;
   m_recalcTimer.stop();
@@ -67,8 +67,7 @@ HTMLImportChild* HTMLImportTreeRoot::add(HTMLImportChild* child) {
 }
 
 HTMLImportChild* HTMLImportTreeRoot::find(const KURL& url) const {
-  for (size_t i = 0; i < m_imports.size(); ++i) {
-    HTMLImportChild* candidate = m_imports[i].get();
+  for (const auto& candidate : m_imports) {
     if (equalIgnoringFragmentIdentifier(candidate->url(), url))
       return candidate;
   }