== Analysis == 
Both change buffer pages and on-disk indexes pages are marked as
FIL_PAGE_INDEX. So all ibuf index pages will classify as INDEX with NULL
table_name and index_name.

== Solution ==
A new page type for ibuf data pages named I_S_PAGE_TYPE_IBUF is defined. All
these pages whose index_id equal (DICT_IBUF_ID_MIN + IBUF_SPACE_ID) will 
classify as IBUF_DATA instead of INDEX in INNODB_BUFFER_PAGE 
and INNODB_BUFFER_PAGE_LRU.

This fix is only for IS reporting, both on-disk and buffer pool structures
keep unchanged.

Approved by both Marko and Jimmy. rb#2334