Vector::insert and Vector::append may use memcpy for POD types.

It will improve performance when POD types are copied, by providing
a missing implementation of VectorCopier and using it in
two places which were previously always taking the "new" allocation
path even though they could have used VectorCopier and used
memcpy for POD types.

NOTRY=true

Review URL: https://codereview.chromium.org/178313002

git-svn-id: svn://svn.chromium.org/blink/trunk@168472 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/wtf/Vector.h

@@ -162,7 +162,8 @@ static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
     template<typename T>
     struct VectorCopier<false, T>
     {
-        static void uninitializedCopy(const T* src, const T* srcEnd, T* dst)
+        template<typename U>
+        static void uninitializedCopy(const U* src, const U* srcEnd, T* dst)
         {
             while (src != srcEnd) {
                 new (NotNull, dst) T(*src);
@@ -179,6 +180,11 @@ static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
         {
             memcpy(dst, src, reinterpret_cast<const char*>(srcEnd) - reinterpret_cast<const char*>(src));
         }
+        template<typename U>
+        static void uninitializedCopy(const U* src, const U* srcEnd, T* dst)
+        {
+            VectorCopier<false, T>::uninitializedCopy(src, srcEnd, dst);
+        }
     };
 
     template <bool canFillWithMemset, typename T>
@@ -962,8 +968,7 @@ static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
         }
         RELEASE_ASSERT(newSize >= m_size);
         T* dest = end();
-        for (size_t i = 0; i < dataSize; ++i)
-            new (NotNull, &dest[i]) T(data[i]);
+        VectorCopier<VectorTraits<T>::canCopyWithMemcpy, T>::uninitializedCopy(data, &data[dataSize], dest);
         m_size = newSize;
     }
 
@@ -1022,8 +1027,7 @@ static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
         RELEASE_ASSERT(newSize >= m_size);
         T* spot = begin() + position;
         TypeOperations::moveOverlapping(spot, end(), spot + dataSize);
-        for (size_t i = 0; i < dataSize; ++i)
-            new (NotNull, &spot[i]) T(data[i]);
+        VectorCopier<VectorTraits<T>::canCopyWithMemcpy, T>::uninitializedCopy(data, &data[dataSize], spot);
         m_size = newSize;
     }