[PATCH] Refactor Matcher<T> and DynTypedMatcher to reduce overhead of casts.

[Manuel Klimek]

================
Comment at: include/clang/ASTMatchers/ASTMatchersInternal.h:288
@@ -368,2 +287,3 @@
 
   /// \brief Returns a unique \p ID for the matcher.
+  typedef std::pair<ast_type_traits::ASTNodeKind, uint64_t> MatcherIDType;
----------------
Can you expand the  comment on why we need to return a pair, so we remember 2 weeks from now :)

http://reviews.llvm.org/D5485