diff -r 000000000000 -r 6474c204b198 js/src/gc/Iteration.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/gc/Iteration.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,137 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jscompartment.h"
+#include "jsgc.h"
+
+#include "gc/GCInternals.h"
+#include "js/HashTable.h"
+#include "vm/Runtime.h"
+
+#include "jscntxtinlines.h"
+#include "jsgcinlines.h"
+
+using namespace js;
+using namespace js::gc;
+
+void
+js::TraceRuntime(JSTracer *trc)
+{
+    JS_ASSERT(!IS_GC_MARKING_TRACER(trc));
+
+    MinorGC(trc->runtime(), JS::gcreason::EVICT_NURSERY);
+    AutoPrepareForTracing prep(trc->runtime(), WithAtoms);
+    MarkRuntime(trc);
+}
+
+static void
+IterateCompartmentsArenasCells(JSRuntime *rt, Zone *zone, void *data,
+                               JSIterateCompartmentCallback compartmentCallback,
+                               IterateArenaCallback arenaCallback,
+                               IterateCellCallback cellCallback)
+{
+    for (CompartmentsInZoneIter comp(zone); !comp.done(); comp.next())
+        (*compartmentCallback)(rt, data, comp);
+
+    for (size_t thingKind = 0; thingKind != FINALIZE_LIMIT; thingKind++) {
+        JSGCTraceKind traceKind = MapAllocToTraceKind(AllocKind(thingKind));
+        size_t thingSize = Arena::thingSize(AllocKind(thingKind));
+
+        for (ArenaIter aiter(zone, AllocKind(thingKind)); !aiter.done(); aiter.next()) {
+            ArenaHeader *aheader = aiter.get();
+            (*arenaCallback)(rt, data, aheader->getArena(), traceKind, thingSize);
+            for (CellIterUnderGC iter(aheader); !iter.done(); iter.next())
+                (*cellCallback)(rt, data, iter.getCell(), traceKind, thingSize);
+        }
+    }
+}
+
+void
+js::IterateZonesCompartmentsArenasCells(JSRuntime *rt, void *data,
+                                        IterateZoneCallback zoneCallback,
+                                        JSIterateCompartmentCallback compartmentCallback,
+                                        IterateArenaCallback arenaCallback,
+                                        IterateCellCallback cellCallback)
+{
+    AutoPrepareForTracing prop(rt, WithAtoms);
+
+    for (ZonesIter zone(rt, WithAtoms); !zone.done(); zone.next()) {
+        (*zoneCallback)(rt, data, zone);
+        IterateCompartmentsArenasCells(rt, zone, data,
+                                       compartmentCallback, arenaCallback, cellCallback);
+    }
+}
+
+void
+js::IterateZoneCompartmentsArenasCells(JSRuntime *rt, Zone *zone, void *data,
+                                       IterateZoneCallback zoneCallback,
+                                       JSIterateCompartmentCallback compartmentCallback,
+                                       IterateArenaCallback arenaCallback,
+                                       IterateCellCallback cellCallback)
+{
+    AutoPrepareForTracing prop(rt, WithAtoms);
+
+    (*zoneCallback)(rt, data, zone);
+    IterateCompartmentsArenasCells(rt, zone, data,
+                                   compartmentCallback, arenaCallback, cellCallback);
+}
+
+void
+js::IterateChunks(JSRuntime *rt, void *data, IterateChunkCallback chunkCallback)
+{
+    AutoPrepareForTracing prep(rt, SkipAtoms);
+
+    for (js::GCChunkSet::Range r = rt->gcChunkSet.all(); !r.empty(); r.popFront())
+        chunkCallback(rt, data, r.front());
+}
+
+void
+js::IterateScripts(JSRuntime *rt, JSCompartment *compartment,
+                   void *data, IterateScriptCallback scriptCallback)
+{
+    MinorGC(rt, JS::gcreason::EVICT_NURSERY);
+    AutoPrepareForTracing prep(rt, SkipAtoms);
+
+    if (compartment) {
+        for (CellIterUnderGC i(compartment->zone(), gc::FINALIZE_SCRIPT); !i.done(); i.next()) {
+            JSScript *script = i.get<JSScript>();
+            if (script->compartment() == compartment)
+                scriptCallback(rt, data, script);
+        }
+    } else {
+        for (ZonesIter zone(rt, SkipAtoms); !zone.done(); zone.next()) {
+            for (CellIterUnderGC i(zone, gc::FINALIZE_SCRIPT); !i.done(); i.next())
+                scriptCallback(rt, data, i.get<JSScript>());
+        }
+    }
+}
+
+void
+js::IterateGrayObjects(Zone *zone, GCThingCallback cellCallback, void *data)
+{
+    MinorGC(zone->runtimeFromMainThread(), JS::gcreason::EVICT_NURSERY);
+    AutoPrepareForTracing prep(zone->runtimeFromMainThread(), SkipAtoms);
+
+    for (size_t finalizeKind = 0; finalizeKind <= FINALIZE_OBJECT_LAST; finalizeKind++) {
+        for (CellIterUnderGC i(zone, AllocKind(finalizeKind)); !i.done(); i.next()) {
+            JSObject *obj = i.get<JSObject>();
+            if (obj->isMarked(GRAY))
+                cellCallback(data, obj);
+        }
+    }
+}
+
+JS_PUBLIC_API(void)
+JS_IterateCompartments(JSRuntime *rt, void *data,
+                       JSIterateCompartmentCallback compartmentCallback)
+{
+    JS_ASSERT(!rt->isHeapBusy());
+
+    AutoTraceSession session(rt);
+
+    for (CompartmentsIter c(rt, WithAtoms); !c.done(); c.next())
+        (*compartmentCallback)(rt, data, c);
+}