add some packages

node_modules/core-js/modules/es7.math.clamp.js

@@ -0,0 +1,8 @@
+// https://rwaldron.github.io/proposal-math-extensions/
+var $export = require('./_export');
+
+$export($export.S, 'Math', {
+  clamp: function clamp(x, lower, upper) {
+    return Math.min(upper, Math.max(lower, x));
+  }
+});