Remove comment discussing non-existent ARRAYSIZE_UNSAFE macro

src/base/macros.h

Index: src/base/macros.h
diff --git a/src/base/macros.h b/src/base/macros.h
index 822c88704a6f7699944504ae78317eb6080c3f41..e3866173be622aca3652d2f5f5ece68b1fee96fd 100644
--- a/src/base/macros.h
+++ b/src/base/macros.h
@@ -21,12 +21,6 @@
 // The expression is a compile-time constant, and therefore can be
 // used in defining new arrays, for example.  If you use arraysize on
 // a pointer by mistake, you will get a compile-time error.
-//
-// One caveat is that arraysize() doesn't accept any array of an
-// anonymous type or a type defined inside a function.  In these rare
-// cases, you have to use the unsafe ARRAYSIZE_UNSAFE() macro below.  This is
-// due to a limitation in C++'s template system.  The limitation might
-// eventually be removed, but it hasn't happened yet.
 #define arraysize(array) (sizeof(ArraySizeHelper(array)))