Fix for bug "Inline Navigator cancel after click pager"

Fix for:
https://github.com/tonytomov/jqGrid/issues/518
Grid with inlineNav.
Edit row (dont save) -> 
Click to disabled pager button "move to the first page" ->
Click to InlineNav cancel button ->
Error "Uncaught TypeError: Cannot read property 'id' of undefined" - savedRow now is empty. 
Also, reproduced in demos.
Merge pull request #519 from goodTrip/master

Fix for bug "Inline Navigator cancel after click pager"