diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/proxy-assign-inherited.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/proxy-assign-inherited.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,21 @@
+// When we assign to a property that a proxy claims is inherited, the
+// defineProperty handler call to create the new own property should get
+// the newly assigned value.
+
+var hits;
+var handlers = {
+  getOwnPropertyDescriptor: function(name) {
+    return undefined;
+  },
+  getPropertyDescriptor: function(name) {
+    return { value:42, writable:true, enumerable:true, configurable:true };
+  },
+  defineProperty: function(name, descriptor) {
+    hits++;
+    assertEq(name, 'x');
+    assertEq(descriptor.value, 43);
+  }
+};
+hits = 0;
+Proxy.create(handlers).x = 43;
+assertEq(hits, 1);
\ No newline at end of file