tools: move eslint from tools to tools/node_modules

This is required because we need to add the babel-eslint dependency
and it has to be able to resolve "eslint".
babel-eslint is required to support future ES features such as async
iterators and import.meta.

Refs: https://github.com/nodejs/node/pull/17755
PR-URL: https://github.com/nodejs/node/pull/17820
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/tools/node_modules/eslint/lib/rules/no-sparse-arrays.js b/tools/node_modules/eslint/lib/rules/no-sparse-arrays.js
new file mode 100644
index 0000000000..3044896c61
--- /dev/null
+++ b/tools/node_modules/eslint/lib/rules/no-sparse-arrays.js
@@ -0,0 +1,43 @@
+/**
+ * @fileoverview Disallow sparse arrays
+ * @author Nicholas C. Zakas
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        docs: {
+            description: "disallow sparse arrays",
+            category: "Possible Errors",
+            recommended: true
+        },
+
+        schema: []
+    },
+
+    create(context) {
+
+
+        //--------------------------------------------------------------------------
+        // Public
+        //--------------------------------------------------------------------------
+
+        return {
+
+            ArrayExpression(node) {
+
+                const emptySpot = node.elements.indexOf(null) > -1;
+
+                if (emptySpot) {
+                    context.report({ node, message: "Unexpected comma in middle of array." });
+                }
+            }
+
+        };
+
+    }
+};