Remove MOJO_STATIC_CONST_MEMBER_DEFINITION.

mojo/public/cpp/system/macros.h

Index: mojo/public/cpp/system/macros.h
diff --git a/mojo/public/cpp/system/macros.h b/mojo/public/cpp/system/macros.h
index 2b6fba8d179dc71707b944198e0d37dd1f8d4d61..0fb076f3e689fd0762e69ced045b72134f58f35e 100644
--- a/mojo/public/cpp/system/macros.h
+++ b/mojo/public/cpp/system/macros.h
@@ -64,29 +64,6 @@ char(&ArraySizeHelper(const T(&array)[N]))[N];
   type(const type&) = delete;                                        \
   void operator=(const type&) = delete
 
-// The C++ standard requires that static const members have an out-of-class
-// definition (in a single compilation unit), but MSVC chokes on this (when
-// language extensions, which are required, are enabled). (You're only likely to
-// notice the need for a definition if you take the address of the member or,
-// more commonly, pass it to a function that takes it as a reference argument --
-// probably an STL function.) This macro makes MSVC do the right thing. See
-// http://msdn.microsoft.com/en-us/library/34h23df8(v=vs.100).aspx for more
-// information. This workaround does not appear to be necessary after VS2015.
-// Use like:
-//
-// In the .h file:
-//   struct Foo {
-//     static const int kBar = 5;
-//   };
-//
-// In the .cc file:
-//   MOJO_STATIC_CONST_MEMBER_DEFINITION const int Foo::kBar;
-#if defined(_MSC_VER) && _MSC_VER < 1900
-#define MOJO_STATIC_CONST_MEMBER_DEFINITION __declspec(selectany)
-#else
-#define MOJO_STATIC_CONST_MEMBER_DEFINITION
-#endif
-
 namespace mojo {
 
 // Used to explicitly mark the return value of a function as unused. (Use this