Use more ArrayRefs

No functional change is intended, just a small refactoring.

llvm-svn: 273647
diff --git a/clang/lib/AST/ASTDumper.cpp b/clang/lib/AST/ASTDumper.cpp
index da7e980..e1d52ea 100644
--- a/clang/lib/AST/ASTDumper.cpp
+++ b/clang/lib/AST/ASTDumper.cpp
@@ -1681,7 +1681,7 @@
 }
 
 void ASTDumper::VisitBlockDecl(const BlockDecl *D) {
-  for (auto I : D->params())
+  for (auto I : D->parameters())
     dumpDecl(I);
 
   if (D->isVariadic())