Allow _.before and _.after to accept func as the first argument

lodash.js

@@ -5760,7 +5760,13 @@
      */
     function after(n, func) {
       if (!isFunction(func)) {
-        throw new TypeError(FUNC_ERROR_TEXT);
+        if (isFunction(n)) {
+          var temp = n;
+          n = func;
+          func = temp;
+        } else {
+          throw new TypeError(FUNC_ERROR_TEXT);
+        }
       }
       n = nativeIsFinite(n = +n) ? n : 0;
       return function() {
@@ -5788,7 +5794,13 @@
     function before(n, func) {
       var result;
       if (!isFunction(func)) {
-        throw new TypeError(FUNC_ERROR_TEXT);
+        if (isFunction(n)) {
+          var temp = n;
+          n = func;
+          func = temp;
+        } else {
+          throw new TypeError(FUNC_ERROR_TEXT);
+        }
       }
       return function() {
         if (--n > 0) {

test/test.js

@@ -800,6 +800,18 @@
       deepEqual(actual, expected);
     });
 
+    test('should allow `func` as the first argument', 1, function() {
+      var count = 0;
+
+      try {
+        var after = _.after(function() { count++; }, 1);
+        after();
+        after();
+      } catch(e) {}
+
+      strictEqual(count, 2);
+    });
+
     test('should not set a `this` binding', 2, function() {
       var after = _.after(1, function() { return ++this.count; }),
           object = { 'count': 0, 'after': after };
@@ -976,6 +988,18 @@
       deepEqual(actual, expected);
     });
 
+    test('should allow `func` as the first argument', 1, function() {
+      var count = 0;
+
+      try {
+        var before = _.before(function() { count++; }, 2);
+        before();
+        before();
+      } catch(e) {}
+
+      strictEqual(count, 1);
+    });
+
     test('should not set a `this` binding', 2, function() {
       var before = _.before(2, function() { return ++this.count; }),
           object = { 'count': 0, 'before': before };