Z-index `-99999` generates `-999991500`

[chris-dura]

global:
  type: z-index
  category: z-index
  cssProperties:
    - z-index

props:
  - Z_INDEX_DEEPDIVE:
    name: 'my-z-index-deepdive'
    value: '-99999'

Output:

// xml
<property name="MY_Z_INDEX_DEEPDIVE" category="z-index">-999991500</property>

// scss
$my-z-index-deepdive: -999991500;

...