Vapour: Removed sessionStorage polyfill check and commented out JAWS aria fixes check

Removed sessionStorage polyfill check since IE8+ supports it. If someone needs to extend support for sessionStorage to IE7 then they can add a sessionStorage polyfill to the oldIE markup block.

Commented out JAWS aria fixes until a final determination is made about its future. Currently the accessibility community is discouraging implementing the fixes (due to possible risks for other screen reader users and the possible performance costs). Leaving as commented out code for now until a final decision is made by the community (some are still reviewing). Related issues are #2968 and #2970.