DeclBase/DeclCXX/DeclTemplate - silence static analyzer getAs<> null dereference warnings. NFCI.

The static analyzer is warning about potential null dereferences, but in these cases we should be able to use castAs<> directly and if not assert will fire for us.

llvm-svn: 373626
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index c03ae22..ccfc292 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -519,15 +519,15 @@
 }
 
 unsigned TemplateTypeParmDecl::getDepth() const {
-  return getTypeForDecl()->getAs<TemplateTypeParmType>()->getDepth();
+  return getTypeForDecl()->castAs<TemplateTypeParmType>()->getDepth();
 }
 
 unsigned TemplateTypeParmDecl::getIndex() const {
-  return getTypeForDecl()->getAs<TemplateTypeParmType>()->getIndex();
+  return getTypeForDecl()->castAs<TemplateTypeParmType>()->getIndex();
 }
 
 bool TemplateTypeParmDecl::isParameterPack() const {
-  return getTypeForDecl()->getAs<TemplateTypeParmType>()->isParameterPack();
+  return getTypeForDecl()->castAs<TemplateTypeParmType>()->isParameterPack();
 }
 
 //===----------------------------------------------------------------------===//