Adding checks for the cases when array grows too big.

test/mjsunit/array-unshift.js

Index: test/mjsunit/array-unshift.js
diff --git a/test/mjsunit/array-unshift.js b/test/mjsunit/array-unshift.js
index 8b357963d9a7149f45ca8918967bb3e66a84999c..06a78a7d9ee8902910a5d7118d045629716b0c1c 100644
--- a/test/mjsunit/array-unshift.js
+++ b/test/mjsunit/array-unshift.js
@@ -114,3 +114,19 @@
   assertTrue(delete Array.prototype[5]);
   assertTrue(delete Array.prototype[7]);
 })();
+
+// Check the behaviour when approaching maximal values for length.
+(function() {
+  for (var i = 0; i < 7; i++) {
+    try {
+      new Array((1 << 32) - 3).unshift(1, 2, 3, 4, 5);
+      throw 'Should have thrown RangeError';
+    } catch (e) {
+      assertTrue(e instanceof RangeError);
+    }
+
+    // Check smi boundary
+    var bigNum = (1 << 30) - 3;
+    assertEquals(bigNum + 7, new Array(bigNum).unshift(1, 2, 3, 4, 5, 6, 7));
+  }
+})();