Remove unused class AssertNoZoneAllocation.

src/zone-inl.h

Index: src/zone-inl.h
diff --git a/src/zone-inl.h b/src/zone-inl.h
index 9a2618c5a8443945ea1a8bf1174bd1ed7127bd54..ee96ec052eb9863201fabbbed2f211b33d8e9c8e 100644
--- a/src/zone-inl.h
+++ b/src/zone-inl.h
@@ -39,19 +39,7 @@ namespace v8 {
 namespace internal {
 
 
-AssertNoZoneAllocation::AssertNoZoneAllocation()
-    : prev_(Isolate::Current()->zone_allow_allocation()) {
-  Isolate::Current()->set_zone_allow_allocation(false);
-}
-
-
-AssertNoZoneAllocation::~AssertNoZoneAllocation() {
-  Isolate::Current()->set_zone_allow_allocation(prev_);
-}
-
-
 inline void* Zone::New(int size) {
-  ASSERT(Isolate::Current()->zone_allow_allocation());
   ASSERT(ZoneScope::nesting() > 0);
   // Round up the requested size to fit the alignment.
   size = RoundUp(size, kAlignment);