Correctly handle non-array receivers in Array length setter.

test/mjsunit/regress/regress-1491.js

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+
+// Test that the Array length accessor correctly deals with non-array
+// receivers.
+
+// Create an object with an array as the prototype.
+var o = Object.create([]);
+
+// Check that writing the length property of the non-array object
+// works as expected.
+var value = "asdf";
+o.length = value;

[Rico, 2011/06/21 07:54:39]

Maybe add assertDoesNotThrow around the assignment to explicitly catch the issue
stated in the bug report (we will fail anyway, but it is more readable what we
are trying to assert).

[Mads Ager (chromium), 2011/06/21 08:00:43]

I'd like to keep it the way it is. I think asserting that we do not throw will
just make the test harder to read. The assert that the correct thing was written
is really what we want and any uncaught exceptions in this code (and all other
tests) is a failure.

+assertEquals(value, o.length);