Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/core-js-pure/internals/get-async-iterator-flattenable.js

@@ -0,0 +1,30 @@
+'use strict';
+var call = require('../internals/function-call');
+var isCallable = require('../internals/is-callable');
+var anObject = require('../internals/an-object');
+var getIteratorDirect = require('../internals/get-iterator-direct');
+var getIteratorMethod = require('../internals/get-iterator-method');
+var getMethod = require('../internals/get-method');
+var wellKnownSymbol = require('../internals/well-known-symbol');
+var AsyncFromSyncIterator = require('../internals/async-from-sync-iterator');
+
+var ASYNC_ITERATOR = wellKnownSymbol('asyncIterator');
+
+module.exports = function (obj) {
+  var object = anObject(obj);
+  var alreadyAsync = true;
+  var method = getMethod(object, ASYNC_ITERATOR);
+  var iterator;
+  if (!isCallable(method)) {
+    method = getIteratorMethod(object);
+    alreadyAsync = false;
+  }
+  if (method !== undefined) {
+    iterator = call(method, object);
+  } else {
+    iterator = object;
+    alreadyAsync = true;
+  }
+  anObject(iterator);
+  return getIteratorDirect(alreadyAsync ? iterator : new AsyncFromSyncIterator(getIteratorDirect(iterator)));
+};