[heap] Synchronize young generation GC with concurrent marking.

src/crankshaft/hydrogen-environment-liveness.cc

Index: src/crankshaft/hydrogen-environment-liveness.cc
diff --git a/src/crankshaft/hydrogen-environment-liveness.cc b/src/crankshaft/hydrogen-environment-liveness.cc
index e1eb11692f1d628c1ee23bd02cbb6de0f4f52010..89b2b7aedef74ba0742ac15e3d329f4792a5c79c 100644
--- a/src/crankshaft/hydrogen-environment-liveness.cc
+++ b/src/crankshaft/hydrogen-environment-liveness.cc
@@ -222,7 +222,7 @@ void HEnvironmentLivenessAnalysisPhase::Run() {
 #ifdef DEBUG
 bool HEnvironmentLivenessAnalysisPhase::VerifyClosures(
     Handle<JSFunction> a, Handle<JSFunction> b) {
-  Heap::RelocationLock for_heap_access(isolate()->heap());
+  base::LockGuard<base::Mutex> guard(isolate()->heap()->relocation_mutex());
   AllowHandleDereference for_verification;
   return a.is_identical_to(b);
 }