Update MOE DB.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81799082
Changing signature of Tx#getTable to accommodate persisted index tables.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81810073
Switch all indices to use B-Tree instead of AA-Tree.

Perf benchmark shows B-Tree indices are significantly faster in bulk
insertion and range queries.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81828355
Writing persisted indices to backing store as part of committing a transaction.

Specifically:
- Adding Journal#getIndexScope() and updating IndexedDB#createTx() to expand
tx's scope to include object stores corresponding to indices.
- Updating BaseTx#mergeIntoBackstore() to store persisted indices to disk.
- Fixing bug in lf.proc.UpdateStep#exec() where the contents of the cache
were accidentally modified (revealed by tests added in this CL).
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81835279
Fixing index persistence in the case of removed rows.

Before this CL, removed rows would remain in the DB erroneously.
The test added in this CL also revealed a bug in ObjectStore#remove.
The returned promise was never fired in the case were all rows in the
object store were removed. Fixed and covered by new tests.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81836850
Reconstructing persisted indices from disk during startup.

- Modifying lf.cache.Prefetcher to reconstruct persisted indices
from disk, instead of reconstructing them from scratch.
- Adding IndexStore#set() interface method, such that after the
indices have been reconstructed they can be registered in IndexStore.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81991426
Fixing MemoryIndexStore#getTableIndices to return the right indices.

It was returning indices belonging to other tables in some cases.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82002473
Attempt deflake BTreeTest#testRandomNumbers on Firefox.

"too much recursion" is thrown sometimes on Firefox. Reducing
the number of rows in the test, reduces the recursion level from
38 to 18 which should eliminate the problem, or at least make it
more rare.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82009691
Respecting enabledBundleMode definition.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82029712