[RFC]vim-patch:7.4.311

Problem:    Can't use winrestview to only restore part of the view.
Solution:   Handle missing items in the dict. (Christian Brabandt)

https://code.google.com/p/vim/source/detail?r=f6f7543043246107075f0d3739c471d51b7226da
This should be `if (dict_find(dict, (char_u *)"leftcol", -1) != NULL) {` to match the read dictionary entry in the next line.