Remove more unsed templates from WTF::TypeTraits.

I left the is_convertible<T> tests in so we can be certain that it
behaves consistently across all build targets.

Bug: 579462
Change-Id: I5e9fc65d53db52356a545360176fb84fa329a2f4
Reviewed-on: https://chromium-review.googlesource.com/780599
Commit-Queue: Yuta Kitamura <yutak@chromium.org>
Reviewed-by: Yuta Kitamura <yutak@chromium.org>
Cr-Commit-Position: refs/heads/master@{#518116}

third_party/WebKit/Source/platform/wtf/TypeTraits.h

@@ -121,49 +121,6 @@ struct IsSubclassOfTemplateTypenameSizeTypename {
   static const bool value = sizeof(SubclassCheck(t_)) == sizeof(YesType);
 };
 
-template <typename T, template <class V> class OuterTemplate>
-struct RemoveTemplate {
-  typedef T Type;
-};
-
-template <typename T, template <class V> class OuterTemplate>
-struct RemoveTemplate<OuterTemplate<T>, OuterTemplate> {
-  typedef T Type;
-};
-
-#if (defined(COMPILER_MSVC) || !GCC_VERSION_AT_LEAST(4, 9, 0)) && \
-    !defined(__clang__)
-// FIXME: MSVC bug workaround. Remove once MSVC STL is fixed.
-// FIXME: GCC before 4.9.0 seems to have the same issue.
-// C++ 2011 Spec (ISO/IEC 14882:2011(E)) 20.9.6.2 Table 51 states that
-// the template parameters shall be a complete type if they are different types.
-// However, MSVC checks for type completeness even if they are the same type.
-// Here, we use a template specialization for same type case to allow incomplete
-// types.
-
-template <typename T, typename U>
-struct IsConvertible {
-  static const bool value = std::is_convertible<T, U>::value;
-};
-
-template <typename T>
-struct IsConvertible<T, T> {
-  static const bool value = true;
-};
-
-#define EnsurePtrConvertibleArgDecl(From, To)                             \
-  typename std::enable_if<WTF::IsConvertible<From*, To*>::value>::type* = \
-      nullptr
-#define EnsurePtrConvertibleArgDefn(From, To) \
-  typename std::enable_if<WTF::IsConvertible<From*, To*>::value>::type*
-#else
-#define EnsurePtrConvertibleArgDecl(From, To)                              \
-  typename std::enable_if<std::is_convertible<From*, To*>::value>::type* = \
-      nullptr
-#define EnsurePtrConvertibleArgDefn(From, To) \
-  typename std::enable_if<std::is_convertible<From*, To*>::value>::type*
-#endif
-
 }  // namespace WTF
 
 namespace blink {

third_party/WebKit/Source/platform/wtf/TypeTraitsTest.cpp

@@ -220,6 +220,10 @@ static_assert(
 static_assert(!IsTriviallyDestructible<DestructorDeleted>::value,
               "DestructorDeleted must not be trivially destructible.");
 
+#define EnsurePtrConvertibleArgDecl(From, To)                              \
+  typename std::enable_if<std::is_convertible<From*, To*>::value>::type* = \
+      nullptr
+
 template <typename T>
 class Wrapper {
  public: