Fix spread operator in ArrayLiterals when nested in other literals

Mark ArrayLiterals utilizing the spread operator as non-simple.
This causes them to return false for IsCompileTimeValue, and thus
causes spread to work as expected in nested literals.

BUG=v8:4417
LOG=y

Review URL: https://codereview.chromium.org/1336123002

Cr-Commit-Position: refs/heads/master@{#30754}

src/ast.cc

@@ -556,7 +556,7 @@ void ArrayLiteral::BuildConstantElements(Isolate* isolate) {
       Strength::WEAK, INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE);
 
   // Fill in the literals.
-  bool is_simple = true;
+  bool is_simple = (first_spread_index_ < 0);
   int depth_acc = 1;
   bool is_holey = false;
   int array_index = 0;

test/mjsunit/harmony/regress/regress-4417.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// Flags: --harmony-spread-arrays
+
+var arr = [1, 2, 3];
+assertEquals({arr: [1, 2, 3]}, {arr: [...arr]});
+assertEquals([[1, 2, 3]], [[...arr]]);
+
+assertEquals({arr: [6, 5, [1, 2, 3]]}, {arr: [6, 5, [...arr]]});
+assertEquals([8, 7, [6, 5, [1, 2, 3]]], [8, 7, [6, 5, [...arr]]]);