Clean up, as suggested by John.

llvm-svn: 142884
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 7e094fd..26ea225 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -3102,7 +3102,7 @@
   case Expr::CXXConstCastExprClass:
   case Expr::ObjCBridgedCastExprClass: {
     const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
-    if (E->getStmtClass() != Expr::ImplicitCastExprClass &&
+    if (isa<ExplicitCastExpr>(E) &&
         isa<FloatingLiteral>(SubExpr->IgnoreParenImpCasts()))
       return NoDiag();
     switch (cast<CastExpr>(E)->getCastKind()) {