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 // Storing a Debugger.Object as a key in a WeakMap protects it from GC as long as

 // the referent is alive.

 var g = newGlobal();

 var N = g.N = 10;

 var dbg = Debugger(g);

 var cache = new WeakMap;

 var i = 0;

 dbg.onDebuggerStatement = function (frame) {

     cache.set(frame.arguments[0], i++);

 };

 g.eval("function f(x) { debugger; }");

 g.eval("var arr = [], j; for (j = 0; j < N; j++) arr[j] = {};");

 g.eval("for (j = 0; j < N; j++) f(arr[j]);");

 assertEq(i, N);

 gc(); gc();

 i = 0;

 dbg.onDebuggerStatement = function (frame) {

     assertEq(cache.get(frame.arguments[0]), i++)

 };

 g.eval("for (j = 0; j < N; j++) f(arr[j]);");

 assertEq(i, N);