jqlite.show() behaves differently from what Jquery does

[Codier]

We made a decision to make jqlite.show() behaves differently from jquery.show().
To be more specific, if there is some cascading rule that prevents an element from showing up and we cannot retrieve its old display attribute value, we just set it to block.
This is very unexpected and causes many surprises and problems.
We probably should revert this commit : #445

[IgorMinar]

we need to isolate the existing issue and see if we can do something about it. I think that reverting is not an option, because the old behavior was also buggy, it just exhibited the bugs in different scenarios.

[IgorMinar]

after a long discussion we agreed that supporting element#show requires too much code so we should left that to jquery

the changes from pull request 445 were reverted in 793ecb4