ENYO-376: Header's adjustTitleWidth checks to make sure the measured client exists before proceeding.

Enyo-DCO-1.1-Signed-off-by: Blake Stephens <blake.stephens@lge.com>
Merge pull request #1728 from enyojs/ENYO-376-blakestephens

ENYO-376: Header's adjustTitleWidth checks for the client before measuring

Reviewed-By: Gray Norton (gray.norton@lge.com)
Integrated-By: Aaron Tam (aaron.tam@lge.com)