[ASTImporter] Support default argument initialization of ParmVarDecls

Patch by Peter Szecsi!

Differential Revision: https://reviews.llvm.org/D29612

llvm-svn: 295654
diff --git a/clang/test/ASTMerge/exprs-cpp/test.cpp b/clang/test/ASTMerge/exprs-cpp/test.cpp
index ba1f18b..0535aa8 100644
--- a/clang/test/ASTMerge/exprs-cpp/test.cpp
+++ b/clang/test/ASTMerge/exprs-cpp/test.cpp
@@ -41,5 +41,7 @@
   testScalarInit(42);
   testOffsetOf();
   testDefaultArg(12);
+  testDefaultArg();
+  testDefaultArgExpr();
   useTemplateType();
 }