[FIX] sap.m.ToggleButton: Toggle hover background color is wrong in Firefox

 In Firefox the button DOM element receives the focus not the inner div. So when the button is hovered this style is applied:
 .sapMBtn:hover > .sapMBtnHoverable
 from blue_crystal's Button.less
 instead of the inner div's hover style from ToggleButton.less

 For all browsers: Also the root DOM element is slightly larger then the inner one, because of the padding. So hovering on the edges, also applies the wrong hover style from above.
 It makes sense that the hover state is received when we are able to click - and that's the case when we hover over the edges.

Fixes https://github.com/SAP/openui5/issues/232

Change-Id: I46bddc52a7b3acc88d20ab7bdebd950cfee21cd8
CR-Id: 012003146900009266372014
(cherry picked from commit 8dddc463cbd6b864851e156cc152ece5f7d1b23e)
Merge "[FIX] sap.m.ToggleButton: Toggle hover background color is wrong in Firefox" into rel-1.26