Removing "using" declarations that import names in the C++ Standard library.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index d3ff7e416ef064d37ab0cf9a617667826fd9bde1..abdff7941209cdabc7de0609edcf6ba23a5a96cc 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -198,7 +198,6 @@
 #include "wtf/text/StringBuffer.h"
 #include "wtf/text/TextEncodingRegistry.h"
 
-using namespace std;
 using namespace WTF;
 using namespace Unicode;
 
@@ -5101,7 +5100,7 @@ void Document::addToTopLayer(Element* element, const Element* before)
     ASSERT(!m_topLayerElements.contains(element));
     ASSERT(!before || m_topLayerElements.contains(before));
     if (before) {
-        size_t beforePosition = m_topLayerElements.find(before);
+        std::size_t beforePosition = m_topLayerElements.find(before);
         m_topLayerElements.insert(beforePosition, element);
     } else {
         m_topLayerElements.append(element);
@@ -5113,7 +5112,7 @@ void Document::removeFromTopLayer(Element* element)
 {
     if (!element->isInTopLayer())
         return;
-    size_t position = m_topLayerElements.find(element);
+    std::size_t position = m_topLayerElements.find(element);
     ASSERT(position != kNotFound);
     m_topLayerElements.remove(position);
     element->setIsInTopLayer(false);
@@ -5380,7 +5379,7 @@ void Document::adjustFloatQuadsForScrollAndAbsoluteZoom(Vector<FloatQuad>& quads
         return;
 
     LayoutRect visibleContentRect = view()->visibleContentRect();
-    for (size_t i = 0; i < quads.size(); ++i) {
+    for (std::size_t i = 0; i < quads.size(); ++i) {
         quads[i].move(-FloatSize(visibleContentRect.x().toFloat(), visibleContentRect.y().toFloat()));
         adjustFloatQuadForAbsoluteZoom(quads[i], renderer);
     }
@@ -5541,8 +5540,8 @@ void Document::updateHoverActiveState(const HitTestRequest& request, Element* in
         }
     }
 
-    size_t removeCount = nodesToRemoveFromChain.size();
-    for (size_t i = 0; i < removeCount; ++i) {
+    std::size_t removeCount = nodesToRemoveFromChain.size();
+    for (std::size_t i = 0; i < removeCount; ++i) {
         nodesToRemoveFromChain[i]->setHovered(false);
         if (event && (ancestorHasCapturingMouseleaveListener || nodesToRemoveFromChain[i]->hasEventListeners(EventTypeNames::mouseleave)))
             nodesToRemoveFromChain[i]->dispatchMouseEvent(*event, EventTypeNames::mouseleave, 0, newHoverNode);
@@ -5559,8 +5558,8 @@ void Document::updateHoverActiveState(const HitTestRequest& request, Element* in
     }
 
     bool sawCommonAncestor = false;
-    size_t addCount = nodesToAddToChain.size();
-    for (size_t i = 0; i < addCount; ++i) {
+    std::size_t addCount = nodesToAddToChain.size();
+    for (std::size_t i = 0; i < addCount; ++i) {
         // Elements past the common ancestor do not change hover state, but might change active state.
         if (ancestorNode && nodesToAddToChain[i] == ancestorNode)
             sawCommonAncestor = true;