Add Array.concat builtin for the most common case.

src/array.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1115 matching lines @@
   // Setup non-enumerable functions of the Array.prototype object and
   // set their names.
   // Manipulate the length of some of the functions to meet
   // expectations set by ECMA-262 or Mozilla.
   InstallFunctionsOnHiddenPrototype($Array.prototype, DONT_ENUM, $Array(
     "toString", getFunction("toString", ArrayToString),
     "toLocaleString", getFunction("toLocaleString", ArrayToLocaleString),
     "join", getFunction("join", ArrayJoin),
     "pop", getFunction("pop", ArrayPop),
     "push", getFunction("push", ArrayPush, 1),
-    "concat", getFunction("concat", ArrayConcat),
+    "concat", getFunction("concat", ArrayConcat, 1),
     "reverse", getFunction("reverse", ArrayReverse),
     "shift", getFunction("shift", ArrayShift),
     "unshift", getFunction("unshift", ArrayUnshift, 1),
     "slice", getFunction("slice", ArraySlice, 2),
     "splice", getFunction("splice", ArraySplice, 2),
     "sort", getFunction("sort", ArraySort),
     "filter", getFunction("filter", ArrayFilter, 1),
     "forEach", getFunction("forEach", ArrayForEach, 1),
     "some", getFunction("some", ArraySome, 1),
     "every", getFunction("every", ArrayEvery, 1),
     "map", getFunction("map", ArrayMap, 1),
     "indexOf", getFunction("indexOf", ArrayIndexOf, 1),
     "lastIndexOf", getFunction("lastIndexOf", ArrayLastIndexOf, 1),
     "reduce", getFunction("reduce", ArrayReduce, 1),
     "reduceRight", getFunction("reduceRight", ArrayReduceRight, 1)
   ));
     
   %FinishArrayPrototypeSetup($Array.prototype);
 }
 
 
 SetupArray();