Fix clang build after r12956
Fix clang build after r12956

That change added a test which called the handlified version of JSObject::SetElement and didn't check the return value, but that method has a MUST_USE_RESULT annotation. This change removes the annotation for consistency with other handlified static methods (like SetProperty).

Review URL: https://chromiumcodereview.appspot.com/11359212
Patch from Adam Klein <adamk@chromium.org>.

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@12963 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh