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

Source/core/editing/CompositeEditCommand.cpp

Index: Source/core/editing/CompositeEditCommand.cpp
diff --git a/Source/core/editing/CompositeEditCommand.cpp b/Source/core/editing/CompositeEditCommand.cpp
index 4f08e61c364d2b4b9364a00163d6d75e069aa8ec..f450f39a50e55eebb6626fb0c77c8c62a4e63225 100644
--- a/Source/core/editing/CompositeEditCommand.cpp
+++ b/Source/core/editing/CompositeEditCommand.cpp
@@ -69,6 +69,8 @@
 #include "core/rendering/RenderListItem.h"
 #include "core/rendering/RenderText.h"
 
+using namespace std;
+
 namespace WebCore {
 
 using namespace HTMLNames;
@@ -760,7 +762,7 @@
         bool indicesIntersect = start <= gapEnd && end >= gapStart;
         int gapLen = gapEnd - gapStart;
         if (indicesIntersect && gapLen > 0) {
-            gapStart = std::max(gapStart, start);
+            gapStart = max(gapStart, start);
             if (str.isNull())
                 str = textNode->data().substring(start, end - start);
             // remove text in the gap