Don't clobber application's strict mode

Applications often configure strict mode in Application.onCreate. A
regression was added in I2614f8bb30203e00953b1978bbcaf24d84d0397b that
applied a strict mode override for a longer period of time than needed.

Test: Launched a few applications
Bug: 36951662
Change-Id: I30b3eafa4a833fc42d0a938da9446007ade80480