Fixing md-tooltip on Firefox issues #3047, #3250 and #3430

[evertonrobertoauler]

var computedStyles = $window.getComputedStyle(element[0]);

console.log(computedStyles['pointer-events'] ); // Firefox returns 'none' as string
console.log(computedStyles['pointer-events'] ); // Chrome returns an empty string ''

The problem is that hasComputedStyleValue('pointer-events','none') always returns true on Firefox and setVisible(true); is not being called.

All the tests are still passing and now the Tooltip works fine on Chrome and Firefox again.

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[ThomasBurleson]

@evertonrobertoauler - I cannot merge this without a signed CLA.

[ThomasBurleson]

This change does not make sense. The three valid pointer-events style values for any HTML element are:

• auto
• inherit
• none

[ThomasBurleson]

Closed with 6fc9212