Revert of Expanding Type Traits to make Vector use mem ops more.

Source/wtf/TypeTraits.h

Index: Source/wtf/TypeTraits.h
diff --git a/Source/wtf/TypeTraits.h b/Source/wtf/TypeTraits.h
index 908f06cf91733e16c98e16f9f751b478e1d138ec..3637304b4680f221d39d09d3591ca9157513150e 100644
--- a/Source/wtf/TypeTraits.h
+++ b/Source/wtf/TypeTraits.h
@@ -29,7 +29,7 @@
     // The following are provided in this file:
     //
     //   IsInteger<T>::value
-    //   IsPod<T>::value
+    //   IsPod<T>::value, see the definition for a note about its limitations
     //   IsConvertibleToInteger<T>::value
     //
     //   IsArray<T>::value
@@ -72,26 +72,6 @@
 
     template<typename T> struct IsArithmetic        { static const bool value = IsInteger<T>::value || IsFloatingPoint<T>::value; };
 
-    template<typename T> struct IsPointer {
-        static const bool value = false;
-    };
-
-    template<typename P> struct IsPointer<const P*> {
-        static const bool value = true;
-    };
-
-    template<typename P> struct IsPointer<P*> {
-        static const bool value = true;
-    };
-
-    template<typename T> struct IsEnum {
-        static const bool value = __is_enum(T);
-    };
-
-    template<typename T> struct IsScalar {
-        static const bool value = IsEnum<T>::value || IsArithmetic<T>::value || IsPointer<T>::value;
-    };
-
     template<typename T> struct IsWeak              { static const bool value = false; };
 
     enum WeakHandlingFlag {
@@ -99,25 +79,10 @@
         WeakHandlingInCollections
     };
 
-    template <typename T> struct IsPod {
-        static const bool value = __is_pod(T);
-    };
-
-    template <typename T> struct IsTriviallyCopyAssignable {
-        static const bool value = __has_trivial_assign(T);
-    };
-
-    template <typename T> struct IsTriviallyMoveAssignable {
-        static const bool value = __has_trivial_assign(T);
-    };
-
-    template <typename T> struct IsTriviallyDefaultConstructible {
-        static const bool value = __has_trivial_constructor(T);
-    };
-
-    template <typename T> struct IsTriviallyDestructible {
-        static const bool value = __has_trivial_destructor(T);
-    };
+    // IsPod is misnamed as it doesn't cover all plain old data (pod) types.
+    // Specifically, it doesn't allow for enums or for structs.
+    template <typename T> struct IsPod              { static const bool value = IsArithmetic<T>::value; };
+    template <typename P> struct IsPod<P*>          { static const bool value = true; };
 
     template<typename T> class IsConvertibleToInteger {
         // Avoid "possible loss of data" warning when using Microsoft's C++ compiler