Bug 1017798 - Part 1: Make AncestorFilter and the TreeMatchContext style scope list include ancestors from following ShadowRoots up to the light tree. r=bzbarsky
Bug 1017798 - Part 2: Set content bits on elements in shadow trees indicating whether they are in a style scope from the light tree. r=bzbarsky
Bug 1017798 - Part 3: Crashtest. r=bzbarsky