[PATCH] Refactor VariantMatcher to use an interface underneath.

[Samuel Benzaquen]

================
Comment at: include/clang/ASTMatchers/Dynamic/VariantValue.h:50
@@ +49,3 @@
+  public:
+    virtual ~MatcherOps();
+    virtual bool canConstructFrom(const DynTypedMatcher &Matcher) const = 0;
----------------
This interface will require some knowledge about VaraidicOperatorMatcherInterface (from D1427) to support that impl.
It will be something like:
  virtual const DynTypedMatcher *constructFromVariadic(ArrayRef<const DynTypedMatcher*>,VariadicOperatorFunction) const = 0;
and will only be used by the variadic impl of Payload.


http://llvm-reviews.chandlerc.com/D1446