Bug 824217 - Remove some easy-to-remove tests of JSRESOLVE_ASSIGNING.  r=bz

--HG--
extra : rebase_source : 2605d559d48b9ccd985bd860f13ab7b1b53ab048
Bug 825692. Avoid layerizing scrollframes that don't have scrollbar boxes. r=roc

Input boxes have overflow:auto but don't have scrollbar boxes. This prevents
us from layerizing them.

--HG--
extra : rebase_source : 24d305a019f67ea2d2529bd25815209bff4485c7
Bug 817921 - Allow webapps to create sub activities. r=blassey