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 95c300f3a948fea72c49eda74ec084c9f6a655ee..d6dc7fb6e48958581790caf642886bf1d191a120 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -23,7 +23,7 @@
 #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 {
 
@@ -1158,7 +1158,7 @@ class Isolate {
 
   interpreter::Interpreter* interpreter() const { return interpreter_; }
 
-  base::AccountingAllocator* allocator() { return allocator_; }
+  AccountingAllocator* allocator() { return allocator_; }
 
   bool IsInAnyContext(Object* object, uint32_t index);
 
@@ -1334,7 +1334,7 @@ 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_;