Bhv 11099 Has improper position for disabled control.

Issue
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If tooltip is showing over disabled control, it could not calculate its position

Cause
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Current position calculation of tooltip is based on `enyo.Spotlight.getCurrent()`
However disabled control could not have spotlight focus. It makes problem.

Fix
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From `onenter` event occur, it preserves event sender and delivers it to `moon.tooltip`.
If `enyo.Spotlight.getCurrent()` is not existed, `adjustPosition()` will use preserved event sender

Enyo-DCO-1.1-Signed-off-by: David Um david.um@lge.com
Hi @aarontam, Thank you for your review.
I found that if we place mouse cursor on disabled `moon.Button` in moon.ToolTipSample`, it shows tooltip well.
However if we move out cursor near tap area instead of moving far away, tooltip could not be shown again.

I'll investigate more based on your advise. Thanks :)