fix(utils): Add guard for undefined navigator

[skjalgepalg]

• Verify existing navigator before referencing in exports from utils

There should be no discernable change for use in browsers. When running in node or similar environments without window, we should no longer cause a referenceError due to undefined navigator as reported in #660

This change would signify a bugfix to the following packages (every package that references utils):

• core-datepicker
• core-dialog
• core-progress
• core-scroll
• core-suggest
• core-tabs
• core-toggle