Ensure _.first supports shortcut fusion. [closes #2447]

lodash.js

@@ -16545,6 +16545,9 @@
     lodash.prototype.reverse = wrapperReverse;
     lodash.prototype.toJSON = lodash.prototype.valueOf = lodash.prototype.value = wrapperValue;
 
+    // Add lazy aliases.
+    lodash.prototype.first = lodash.prototype.head;
+
     if (iteratorSymbol) {
       lodash.prototype[iteratorSymbol] = wrapperToIterator;
     }