If marking system stack is unknown, be more forgiving about stack depths.

third_party/WebKit/Source/platform/heap/TraceTraits.h

Index: third_party/WebKit/Source/platform/heap/TraceTraits.h
diff --git a/third_party/WebKit/Source/platform/heap/TraceTraits.h b/third_party/WebKit/Source/platform/heap/TraceTraits.h
index 75ecd1690be4b4bdb18c9b6785cbee3278e729bd..561835589a84ce394cf1a56ef26578b2ffd04ed8 100644
--- a/third_party/WebKit/Source/platform/heap/TraceTraits.h
+++ b/third_party/WebKit/Source/platform/heap/TraceTraits.h
@@ -57,12 +57,7 @@ public:
             // but test and appropriately handle them should they occur
             // in release builds.
             //
-            // ASan adds extra stack usage, so disable the assert when it is
-            // enabled so as to avoid testing against a much lower & too low,
-            // stack depth threshold.
-#if !defined(ADDRESS_SANITIZER)
-            ASSERT(!StackFrameDepth::isEnabled() || StackFrameDepth::isSafeToRecurse());
-#endif
+            ASSERT(StackFrameDepth::isAcceptableStackUse());
             if (LIKELY(StackFrameDepth::isSafeToRecurse())) {
                 if (visitor->ensureMarked(t)) {
                     TraceTrait<T>::trace(visitor, const_cast<T*>(t));