add checking for design/code button highlighting in screens tests.
add checking for design/code button highlighting in screens tests.

pickettd/code-dot-org,pickettd/code-dot-org,rvarshney/code-dot-org,dillia23/code-dot-org,rvarshney/code-dot-org,ty-po/code-dot-org,rvarshney/code-dot-org,pickettd/code-dot-org,dillia23/code-dot-org,dillia23/code-dot-org,dillia23/code-dot-org,rvarshney/code-dot-org,ty-po/code-dot-org,dillia23/code-dot-org,dillia23/code-dot-org,rvarshney/code-dot-org,ty-po/code-dot-org,ty-po/code-dot-org,rvarshney/code-dot-org,ty-po/code-dot-org,ty-po/code-dot-org,pickettd/code-dot-org,pickettd/code-dot-org,pickettd/code-dot-org,dillia23/code-dot-org,pickettd/code-dot-org,ty-po/code-dot-org,rvarshney/code-dot-org,dillia23/code-dot-org,rvarshney/code-dot-org,pickettd/code-dot-org,ty-po/code-dot-org