Adding a component context stack for rendering, used to prune rerenders to only
    top-level containers.  That is, if the rerender component list includes both X
    and Y, where Y is a rendered child contained by X, only X will "actualy" be
    rerendered.

    @rev goliver@
    @bug W-2052295@
Merging origin/fabbott/master-pending-iterationReRenderSmart into master