Update V8 to r5388 as required by WebKit r66666

Change-Id: Ib3c42e9b7226d22c65c7077c543fe31afe62a318
diff --git a/src/ic.h b/src/ic.h
index a02f272..17450cc 100644
--- a/src/ic.h
+++ b/src/ic.h
@@ -123,8 +123,8 @@
                                                             JSObject* holder);
   static inline InlineCacheHolderFlag GetCodeCacheForObject(JSObject* object,
                                                             JSObject* holder);
-  static inline Map* GetCodeCacheMap(Object* object,
-                                     InlineCacheHolderFlag holder);
+  static inline JSObject* GetCodeCacheHolder(Object* object,
+                                             InlineCacheHolderFlag holder);
 
  protected:
   Address fp() const { return fp_; }