Ensure _.spread doesn’t include arguments after those spread. [closes #2825]

fp/_baseConvert.js

@@ -1,6 +1,9 @@
 var mapping = require('./_mapping'),
     fallbackHolder = require('./placeholder');
 
+/** Built-in value reference. */
+var push = Array.prototype.push;
+
 /**
  * Creates a function, with an arity of `n`, that invokes `func` with the
  * arguments it receives.
@@ -61,6 +64,36 @@ function createCloner(func) {
   };
 }
 
+/**
+ * This function is like `_.spread` except that it includes arguments after those spread.
+ *
+ * @private
+ * @param {Function} func The function to spread arguments over.
+ * @param {number} start The start position of the spread.
+ * @returns {Function} Returns the new function.
+ */
+function spread(func, start) {
+  return function() {
+    var length = arguments.length,
+        args = Array(length);
+
+    while (length--) {
+      args[length] = arguments[length];
+    }
+    var array = args[start],
+        lastIndex = args.length - 1,
+        otherArgs = args.slice(0, start);
+
+    if (array) {
+      push.apply(otherArgs, array);
+    }
+    if (start != lastIndex) {
+      push.apply(otherArgs, args.slice(start + 1));
+    }
+    return func.apply(this, otherArgs);
+  };
+}
+
 /**
  * Creates a function that wraps `func` and uses `cloner` to clone the first
  * argument it receives.
@@ -141,7 +174,6 @@ function baseConvert(util, name, func, options) {
     'iteratee': util.iteratee,
     'keys': util.keys,
     'rearg': util.rearg,
-    'spread': util.spread,
     'toInteger': util.toInteger,
     'toPath': util.toPath
   };
@@ -155,7 +187,6 @@ function baseConvert(util, name, func, options) {
       isFunction = helpers.isFunction,
       keys = helpers.keys,
       rearg = helpers.rearg,
-      spread = helpers.spread,
       toInteger = helpers.toInteger,
       toPath = helpers.toPath;