Add node modules and compiled JavaScript from main (#54)

Co-authored-by: Oliver King <oking3@uncc.edu>

node_modules/underscore/modules/isWeakMap.js

@@ -0,0 +1,5 @@
+import tagTester from './_tagTester.js';
+import { isIE11 } from './_stringTagBug.js';
+import { ie11fingerprint, weakMapMethods }  from './_methodFingerprint.js';
+
+export default isIE11 ? ie11fingerprint(weakMapMethods) : tagTester('WeakMap');