Rename the MapLookupHashIndex builtin to FindOrderedHashMapEntry and
also rename the TurboFan operators LookupHashStorageIndex and
LookupSigned32HashStorageIndex to FindOrderedHashMapEntry and
FindOrderedHashMapEntryForInt32Key respectively. This way the naming is
more consistent and it's immediately obvious from the operator name that
this operator deals with OrderedHashMaps, which wasn't clear before.

Also fix the result of the operation to be either -1 or the index of
the entry relative to the hash table start (that is, no longer eagerly
add hash table start plus value offset to the entry index). This removes
this non-foldable integer additon from TurboFan code for both Map#get
and Map#has.

Drive-by-fix: Also provide more concrete types for the
FindOrderedHashMapEntry operators.

Bug: v8:5049
Change-Id: I418d107b806f3031a52a525cffc20456dc2342db
Reviewed-on: https://chromium-review.googlesource.com/707414Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48404}