Moved zones and zone related stuff in its own directory.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index d8a50c15679658644eb267fbf4d19ce9def9d037..4db41b5fa324a108b2754d7f9391969879048f16 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -23,12 +23,11 @@
 #include "src/messages.h"
 #include "src/regexp/regexp-stack.h"
 #include "src/runtime/runtime.h"
-#include "src/zone.h"
+#include "src/zone/zone.h"
 
 namespace v8 {
 
 namespace base {
-class AccountingAllocator;
 class RandomNumberGenerator;
 }
 
@@ -1160,7 +1159,7 @@ class Isolate {
 
   interpreter::Interpreter* interpreter() const { return interpreter_; }
 
-  base::AccountingAllocator* allocator() { return allocator_; }
+  AccountingAllocator* allocator() { return allocator_; }
 
   bool IsInAnyContext(Object* object, uint32_t index);
 
@@ -1336,7 +1335,7 @@ class Isolate {
   HandleScopeData handle_scope_data_;
   HandleScopeImplementer* handle_scope_implementer_;
   UnicodeCache* unicode_cache_;
-  base::AccountingAllocator* allocator_;
+  AccountingAllocator* allocator_;
   Zone* runtime_zone_;
   InnerPointerToCodeCache* inner_pointer_to_code_cache_;
   GlobalHandles* global_handles_;