Remove typedef which is unused after r159189.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159224 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index d81151d..f92639f 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -363,10 +363,6 @@
     /// NextCallIndex - The next call index to assign.
     unsigned NextCallIndex;
 
-    // Note that we intentionally use std::map here so that references
-    // to values are stable.
-    typedef std::map<const OpaqueValueExpr*, APValue> MapTy;
-
     /// BottomFrame - The frame in which evaluation started. This must be
     /// initialized after CurrentCall and CallStackDepth.
     CallStackFrame BottomFrame;