Revert "Enable and demonstrate Java 9 language features in libcore."

This reverts commit 8e1ef5143df1ce5f84c190030068008089f0af4d.

Fixes: 115656946
Bug: 112443425
Reason for revert: b/115656946

Change-Id: I1d95b2125327515eb0a4f2b276d4bce9b8aa74df
6 files changed