This adds a new external_pointer field to every JSDataView instance
which points directly into the backing store at the given view's
byte_offset. This was the DataView performance is now almost on
par with the TypedArray performance for accessing aligned memory
(with appropriate endianess). This also serves as prepatory work
to enable full 64-bit addressing of DataView backing stores in
optimized code (soonish).

This change optimizes the bounds checking sequence in TurboFan in
such a way that it further improves the DataView set/get performance
by around 10%, almost closing the remaining gap between DataViews
and TypedArrays.

Drive-by-fix: Get rid of the code duplication around DataView inlining
in the JSCallReducer and have only a single bottleneck method now.

Bug: chromium:225811, v8:4153, v8:7881, v8:8171
Change-Id: I9118efd4d19e93f0e51c931a9bec1a56a0f4593e
Reviewed-on: https://chromium-review.googlesource.com/1231994
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56042}