Change in G131 per LC-2948

https://www.w3.org/2006/02/lc-comments-tracker/35422/WD-WCAG20-TECHS-20140724/2948
changes to G128 per LC-2947

https://www.w3.org/2006/02/lc-comments-tracker/35422/WD-WCAG20-TECHS-20140724/2947
Changes to Understand 1.4.3 per LC-2949

https://www.w3.org/2006/02/lc-comments-tracker/35422/WD-UNDERSTANDING-WCAG20-20140724/2949