few small analyzer AST visitor fixes

pkg/analyzer/lib/src/generated/ast.dart

Index: pkg/analyzer/lib/src/generated/ast.dart
diff --git a/pkg/analyzer/lib/src/generated/ast.dart b/pkg/analyzer/lib/src/generated/ast.dart
index c386c83fcab0672f524116a05d294237a7b8c1f6..9802e2a714a876afc48acd71346afbd3e67a29d3 100644
--- a/pkg/analyzer/lib/src/generated/ast.dart
+++ b/pkg/analyzer/lib/src/generated/ast.dart
@@ -1617,7 +1617,8 @@ class AstCloner implements AstVisitor<AstNode> {
 
   @override
   VariableDeclarationList visitVariableDeclarationList(
-      VariableDeclarationList node) => new VariableDeclarationList(null,
+      VariableDeclarationList node) => new VariableDeclarationList(
+      cloneNode(node.documentationComment),
       cloneNodeList(node.metadata), cloneToken(node.keyword),
       cloneNode(node.type), cloneNodeList(node.variables));