Fix some missing includes and forward declarations.

R=yangguo@chromium.org
BUG=

Review URL: https://codereview.chromium.org/214903002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20314 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/circular-queue.h

@@ -28,6 +28,7 @@
 #ifndef V8_CIRCULAR_QUEUE_H_
 #define V8_CIRCULAR_QUEUE_H_
 
+#include "atomicops.h"
 #include "v8globals.h"
 
 namespace v8 {

src/v8globals.h

@@ -133,6 +133,7 @@ class Heap;
 class HeapObject;
 class IC;
 class InterceptorInfo;
+class Isolate;
 class JSReceiver;
 class JSArray;
 class JSFunction;