diff --git a/src/compiler.h b/src/compiler.h
index ea74d60..181446b 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -167,6 +167,7 @@
 
   void Initialize(Mode mode) {
     mode_ = V8::UseCrankshaft() ? mode : NONOPT;
+    ASSERT(!script_.is_null());
     if (script_->type()->value() == Script::TYPE_NATIVE) {
       MarkAsNative();
     }
@@ -195,6 +196,7 @@
   // Is this a function from our natives.
   class IsNative: public BitField<bool, 6, 1> {};
 
+
   unsigned flags_;
 
   // Fields filled in by the compilation pipeline.
@@ -292,24 +294,6 @@
 };
 
 
-// During compilation we need a global list of handles to constants
-// for frame elements.  When the zone gets deleted, we make sure to
-// clear this list of handles as well.
-class CompilationZoneScope : public ZoneScope {
- public:
-  CompilationZoneScope(Isolate* isolate, ZoneScopeMode mode)
-      : ZoneScope(isolate, mode) {}
-
-  virtual ~CompilationZoneScope() {
-    if (ShouldDeleteOnExit()) {
-      Isolate* isolate = Isolate::Current();
-      isolate->frame_element_constant_list()->Clear();
-      isolate->result_constant_list()->Clear();
-    }
-  }
-};
-
-
 } }  // namespace v8::internal
 
 #endif  // V8_COMPILER_H_