It started in 0.2.0 also known as demo version. If you fly or bild to sky level you can cross the old world invisible bedrock barrier!
MCPE-8425
In an old world, if you go above sky level, you can cross the barrier of invisible bedrock.
Resolved
Works As Intended
1
(Unassigned)
Unconfirmed
Tablet - Android - Samsung Galaxy Tab S
Android 5.0.2
0.11.0 Beta 9
Retrieved
Works As Intended. See the comment by @unknown in MCPE-261.