Fix bug in Debug::hasAnyLiveHooks.

js/src/jit-test/tests/debug/gc-08.js

@@ -0,0 +1,22 @@
+// |jit-test| debug
+// Debuggers with enabled throw hooks should not be GC'd even if they are
+// otherwise unreachable.
+
+load(libdir + "asserts.js");
+
+var g = newGlobal('new-compartment');
+var actual = 0;
+var expected = 0;
+
+function f() {
+    for (var i = 0; i < 20; i++) {
+        var dbg = new Debug(g);
+        dbg.hooks = {num: i, throw: function (stack, exc) { actual += this.num; }};
+        expected += i;
+    }
+}
+
+f();
+gc();
+assertThrowsValue(function () { g.eval("throw 'fit';"); }, "fit");
+assertEq(actual, expected);

js/src/jsdbg.h

@@ -214,7 +214,7 @@ class Debug {
 bool
 Debug::hasAnyLiveHooks() const
 {
-    return observesDebuggerStatement();
+    return enabled && (hasDebuggerHandler || hasThrowHandler);
 }
 
 bool