fix crash on amazon product page

src/browser/tests/document/get_elements_by_tag_name.html

@@ -153,3 +153,11 @@
 }
 </script>
 
+<script id=list_caching>
+  {
+    // this ordering used to crash
+    const list = document.getElementsByTagName('div');
+    testing.expectEqual('0', list[0].textContent);
+    testing.expectEqual(3, list.length);
+  }
+</script>

src/browser/webapi/collections/node_live.zig

@@ -114,8 +114,11 @@ pub fn NodeLive(comptime mode: Mode) type {
                 if (self._last_length) |cached_length| {
                     return cached_length;
                 }
+                // not ideal, but this can happen if list[x] is called followed
+                // by list.length.
+                self._tw.reset();
+                self._last_index = 0;
             }
-
             // If we're here, it means it's either the first time we're called
             // or the DOM version has changed. Either way, the _tw should be
             // at the start position. It's important that self._last_index == 0