Revert "Exclude isolated_app from ptrace self."

Google Breakpad (crash reporter for Chrome) relies on ptrace
functionality. Without the ability to ptrace, the crash reporter
tool is broken.

Addresses the following denial:

  type=1400 audit(1428619926.939:1181): avc: denied { ptrace } for pid=10077 comm="CrRendererMain" scontext=u:r:isolated_app:s0:c512,c768 tcontext=u:r:isolated_app:s0:c512,c768 tclass=process permissive=0

This reverts commit e9623d8f.

Bug: 20150694
Bug: https://code.google.com/p/chromium/issues/detail?id=475270
Change-Id: I1727c6a93f10ea6db877687a8f81ec789f9e501f