Get rid of ZoneScope completely.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 575afaaf0b2c74513585952c1315f41d07a0eaa3..fbceaf921bb6f996ca7afab19996c51ce9c086f3 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -546,7 +546,6 @@ static bool DebuggerWantsEagerCompilation(CompilationInfo* info,
 
 static Handle<SharedFunctionInfo> MakeFunctionInfo(CompilationInfo* info) {
   Isolate* isolate = info->isolate();
-  ZoneScope zone_scope(info->zone(), DELETE_ON_EXIT);
   PostponeInterruptsScope postpone(isolate);
 
   ASSERT(!isolate->native_context().is_null());
@@ -910,8 +909,6 @@ static bool InstallCodeFromOptimizedCodeMap(CompilationInfo* info) {
 bool Compiler::CompileLazy(CompilationInfo* info) {
   Isolate* isolate = info->isolate();
 
-  ZoneScope zone_scope(info->zone(), DELETE_ON_EXIT);
-
   // The VM is in the COMPILER state until exiting this function.
   VMState<COMPILER> state(isolate);
 
@@ -1228,7 +1225,7 @@ void Compiler::RecordFunctionCompilation(Logger::LogEventsAndTags tag,
 CompilationPhase::CompilationPhase(const char* name,
                                    Isolate* isolate,
                                    Zone* zone)
-    : name_(name), isolate_(isolate), zone_scope_(zone, DELETE_ON_EXIT) {
+    : name_(name), isolate_(isolate), zone_(zone) {
   if (FLAG_hydrogen_stats) {
     start_allocation_size_ = zone->allocation_size();
     start_ticks_ = OS::Ticks();