Delete unused SingletonImmutableBiMap(Entry) constructor.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76173755
Investigate possible deduplication between RegularImmutableMap and RegularImmutableBiMap.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76176371
Factor out an array-backed ImmutableMapEntrySet to use in RegularImmutableMap and RegularImmutableBiMap.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76182964
TerminalEntry's constructor already calls checkEntryNotNull; no need to do it again.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76188203
copyOfEnumMap only gets called with an EnumMap, so narrow its parameter type from Map to EnumMap.

This also makes it clearer that copyOf on an empty EnumMap will succeed.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76190743
Dedup conflict checks and get(Object) implementation between RegularImmutableMap and RegularImmutableBiMap.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76194662
Simplify ImmutableMap.asMultimap().
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76196628
Return to scrubbing cgdecker's username, which we temporarily stopped doing in 69045357f5b4.
We will finally stop scrubbing it again when the standard MOE binary is rebuilt with CL 75843182.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76253324
Eliminate varargs-accepting create() method, which was never called with multiple arguments.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76264541
Reuse ImmutableMap.EMPTY_ENTRY_ARRAY in other ImmutableMap types
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76267320
Establish RangeMap iteration order, as per Guava issue 1842.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76272760