restore extra slot in sentinal array that was removed in 3825. This extra value is read, but not acted-upon, by spanRec.init(), and so we need to have a valid address/slot allocated.
restore extra slot in sentinal array that was removed in 3825. This extra value
is read, but not acted-upon, by spanRec.init(), and so we need to have a valid
address/slot allocated.

Caught by the remoting_unittests in chrome run using ASAN.
Review URL: https://codereview.appspot.com/6176045

git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@3830 2bbb7eff-a529-9590-31e7-b0007b416f81

Hankuo/color-emoji.skia,hbwhlklive/color-emoji.skia,hbwhlklive/color-emoji.skia,Hankuo/color-emoji.skia,Frankie-666/color-emoji.skia,Hankuo/color-emoji.skia,MatChung/color-emoji.skia,hbwhlklive/color-emoji.skia,Frankie-666/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,Hankuo/color-emoji.skia,hbwhlklive/color-emoji.skia,Hankuo/color-emoji.skia,MatChung/color-emoji.skia,MatChung/color-emoji.skia,hbwhlklive/color-emoji.skia,MatChung/color-emoji.skia,Hankuo/color-emoji.skia,Frankie-666/color-emoji.skia,hbwhlklive/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,Frankie-666/color-emoji.skia