Fixes for various failing tests

This is a fix for some failing tests.

* Recently a developer warning about layout values needing to be numeric was adding, but there are some other valid layout property values such as "auto", "1rad" (rotation*), "2,3" (scale). The warning conditions have now been corrected to allow for such values.
* Fixed mouse event related tests where "which", "pageX" and "pageY" needed to be specified in some conditions.
* Added a sanity check into grid view layout computation to avoid NaN layout property values.