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

[NAKAMURA Takumi]

Excuse me, I reverted it in r218648, for now.

- MSC17 doesn't compile it.

  clang/include/clang/ASTMatchers/ASTMatchersInternal.h(387) : error C4519: default template arguments are only allowed on a class template

- g++-4.7.2 reported so many warnings. See also http://bb.pgr.jp/builders/clang-3stage-x86_64-linux/builds/7720/steps/stage1_build

REPOSITORY
  rL LLVM

http://reviews.llvm.org/D5485