Fixes an error when displaying the current layout test index.

This fixes a bug in commit https://android-git.corp.google.com/g/#change,52518.
Updated index to be zero based when passed around and off by one error on
resume. Note that previous commit changes how DumpRenderTree dumps titles.
This might affect the results of layout tests.

Change-Id: I3d6989d71c336f90168e38c994dd36743bda365c