Revert "Do not allow isolated_app to directly open app data files."

This is causing the version of Chrome in Android's tree to crash. The
version of Chrome in Android's tree does not have the following patch:
https://codereview.chromium.org/630123003

Until Chrome updates the version in Android's tree, we need to revert.

Works around the following denials:

audit(0.0:19): avc: denied { search } for name="com.android.chrome" dev="mmcblk0p28" ino=1474658 scontext=u:r:isolated_app:s0:c512,c768 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir
audit(0.0:20): avc: denied { getattr } for path="/data/data/com.android.chrome" dev="mmcblk0p28" ino=1474658 scontext=u:r:isolated_app:s0:c512,c768 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir
audit(0.0:21): avc: denied { getattr } for path="/data/data/com.android.chrome" dev="mmcblk0p28" ino=1474658 scontext=u:r:isolated_app:s0:c512,c768 tcontext=u:object_r:app_data_file:s0:c512,c768 tclass=dir

This reverts commit 669a9773.

Bug: 18006219
Change-Id: Id44137ec6a0dfe4a597b34ab3dad9e3feecc2a5e