Remove insertRange.

pkg/yaml/lib/parser.dart

Index: pkg/yaml/lib/parser.dart
diff --git a/pkg/yaml/lib/parser.dart b/pkg/yaml/lib/parser.dart
index 9621b135d044ed23a3f0832437897fade114d047..b923fe3301df40de0e4e1e6978be0d8a594bcf87 100644
--- a/pkg/yaml/lib/parser.dart
+++ b/pkg/yaml/lib/parser.dart
@@ -1637,7 +1637,7 @@ class _Parser {
         if (!truth(s_indent(indent))) return null;
         return c_l_blockSeqEntry(indent);
       }));
-    content.insertRange(0, 1, first);
+    content.insert(0, first);
 
     return new _SequenceNode("?", content);
   });
@@ -1720,7 +1720,7 @@ class _Parser {
         if (!truth(s_indent(indent))) return null;
         return ns_l_blockMapEntry(indent);
       }));
-    pairs.insertRange(0, 1, first);
+    pairs.insert(0, first);
 
     return map(pairs);
   });