Use border box sizing for MockTextBox (#1721)
Use border box sizing for MockTextBox (#1721)

Change-Id: Ic374dbabd9fad57c06b1b070ab3d84a63ba0b4e6
mit-cml/appinventor-sources,josmas/app-inventor,marksherman/appinventor-sources,mit-cml/appinventor-sources,halatmit/appinventor-sources,marksherman/appinventor-sources,jisqyv/appinventor-sources,josmas/app-inventor,mit-dig/punya,kkashi01/appinventor-sources,kkashi01/appinventor-sources,mit-dig/punya,jisqyv/appinventor-sources,puravidaapps/appinventor-sources,marksherman/appinventor-sources,halatmit/appinventor-sources,jisqyv/appinventor-sources,jisqyv/appinventor-sources,ewpatton/appinventor-sources,kkashi01/appinventor-sources,mit-cml/appinventor-sources,josmas/app-inventor,ewpatton/appinventor-sources,puravidaapps/appinventor-sources,kkashi01/appinventor-sources,ewpatton/appinventor-sources,mit-dig/punya,josmas/app-inventor,ewpatton/appinventor-sources,marksherman/appinventor-sources,mit-cml/appinventor-sources,puravidaapps/appinventor-sources,puravidaapps/appinventor-sources,puravidaapps/appinventor-sources,mit-dig/punya,barreeeiroo/appinventor-sources,mit-dig/punya,kkashi01/appinventor-sources,marksherman/appinventor-sources,mit-dig/punya,jisqyv/appinventor-sources,ewpatton/appinventor-sources,josmas/app-inventor,kkashi01/appinventor-sources,marksherman/appinventor-sources,halatmit/appinventor-sources,barreeeiroo/appinventor-sources,mit-cml/appinventor-sources,halatmit/appinventor-sources,mit-dig/punya,jisqyv/appinventor-sources,barreeeiroo/appinventor-sources,barreeeiroo/appinventor-sources,ewpatton/appinventor-sources,josmas/app-inventor,barreeeiroo/appinventor-sources,halatmit/appinventor-sources,halatmit/appinventor-sources,mit-cml/appinventor-sources