Under certain circustances the number of DOM children is not the same than the number of options,
this causes an exception by access to undefined during iteration.
Use the mode instead of the sass variable to determine which color the
buttons in a toolbar should be based on the background color. Added
error messages when anything other than a color is passed and more
comments.
BREAKING CHANGES: ios mode `$toolbar-ios-button-color` now has a
default value of `color-contrast($colors-ios, $toolbar-ios-background,
ios)` which will evaluate to the primary color for light background
toolbars and white for dark background toolbars.
fixes#6364
BREAKING CHANGES:
`$bar-button-ios-color` has been renamed to `$toolbar-ios-button-color`
`$bar-button-ios-border-radius` has been renamed to
`$toolbar-ios-button-border-radius`
added variables for the toolbar ios title for easier styling:
```
$toolbar-ios-title-font-weight
$toolbar-ios-title-text-align
$toolbar-ios-title-text-color
```
references #6364
BREAKING CHANGES:
`$bar-button-wp-color` was renamed to `$toolbar-wp-button-color`
`$bar-button-wp-border-radius` was renamed to
`$toolbar-wp-button-border-radius`
Added `$toolbar-wp-title-text-color` for better control of the title
color
Removed `$toolbar-wp-button-color` from the default themes
references #6364
BREAKING CHANGES:
`$toolbar-md-button-color` no longer gets passed to the function that
sets the contrast color for toolbar buttons, but it can still be used
to set the default button color.
`$bar-button-md-color` was renamed to `$toolbar-md-button-color`
`$bar-button-md-border-radius` was renamed to
`$toolbar-md-button-border-radius`
references #6364
BREAKING CHANGES: renamed Sass variables in toggle, checkbox, and
radio. Changed `media` in `component-mode-media-padding` (for example)
to `item-left`.
references #5925
