diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/Debugger-multi-02.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/Debugger-multi-02.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,32 @@
+// Test adding hooks during dispatch. The behavior is deterministic and "nice",
+// but mainly what we are checking here is that we do not crash due to
+// modifying a data structure while we're iterating over it.
+
+var g = newGlobal();
+var n = 0;
+var hits;
+
+function addDebugger() {
+    var dbg = new Debugger(g);
+    dbg.onDebuggerStatement = function (stack) {
+        hits++;
+        addDebugger();
+    };
+}
+
+addDebugger();  // now there is one enabled Debugger
+hits = 0;
+g.eval("debugger;");  // after this there are two
+assertEq(hits, 1);
+
+hits = 0;
+g.eval("debugger;");  // after this there are four
+assertEq(hits, 2);
+
+hits = 0;
+g.eval("debugger;");  // after this there are eight
+assertEq(hits, 4);
+
+hits = 0;
+g.eval("debugger;");
+assertEq(hits, 8);