Fix handling of foreign callbacks in DefineOwnProperty.

test/mjsunit/regress/regress-1530.js

+// Copyright 2011 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:
+//
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+//     * Redistributions in binary form must reproduce the above
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+//       with the distribution.
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+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
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+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test that redefining the 'prototype' property of a function object
+// does actually set the internal value and does not screw up any
+// shadowing between said property and the internal value.
+
+var f = function() {};
+
+// Verify that normal assignment of 'prototype' property works properly
+// and updates the internal value.
+var x = { foo: 'bar' };
+f.prototype = x;
+assertSame(f.prototype, x);
+assertSame(f.prototype.foo, 'bar');
+assertSame(new f().foo, 'bar');
+assertSame(Object.getPrototypeOf(new f()), x);
+assertSame(Object.getOwnPropertyDescriptor(f, 'prototype').value, x);
+
+// Verify that 'prototype' behaves like a data property when it comes to
+// redefining with Object.defineProperty() and the internal value gets
+// updated.
+var y = { foo: 'baz' };
+Object.defineProperty(f, 'prototype', { value: y, writable: true });
+assertSame(f.prototype, y);
+assertSame(f.prototype.foo, 'baz');
+assertSame(new f().foo, 'baz');
+assertSame(Object.getPrototypeOf(new f()), y);
+assertSame(Object.getOwnPropertyDescriptor(f, 'prototype').value, y);
+
+// Verify that the previous redefinition didn't screw up callbacks and
+// the internal value still gets updated.
+var z = { foo: 'other' };
+f.prototype = z;
+assertSame(f.prototype, z);
+assertSame(f.prototype.foo, 'other');
+assertSame(new f().foo, 'other');
+assertSame(Object.getPrototypeOf(new f()), z);
+assertSame(Object.getOwnPropertyDescriptor(f, 'prototype').value, z);
+
+// Verify that non-writability of other properties is respected.
+assertThrows("Object.defineProperty(f, 'name', { value: {} })");
+assertThrows("Object.defineProperty(f, 'length', { value: {} })");
+assertThrows("Object.defineProperty(f, 'caller', { value: {} })");
+assertThrows("Object.defineProperty(f, 'arguments', { value: {} })");