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/es-abstract/2018/ToLength.js

@@ -0,0 +1,14 @@
+'use strict';
+
+var MAX_SAFE_INTEGER = require('math-intrinsics/constants/maxSafeInteger');
+
+var ToInteger = require('./ToInteger');
+
+// https://262.ecma-international.org/6.0/#sec-tolength
+
+module.exports = function ToLength(argument) {
+	var len = ToInteger(argument);
+	if (len <= 0) { return 0; } // includes converting -0 to +0
+	if (len > MAX_SAFE_INTEGER) { return MAX_SAFE_INTEGER; }
+	return len;
+};