TypedArrayElementsInfo now represents an element's size as a log 2 and typed as
uintptr.  This simplifies and speeds up (avoids possible HeapNumber allocations) a
number of calculations:

  - Number of Elements (length) -> Byte Length - is now a WordShl
  - Byte Length -> Number of Elements (length) - is now a WordShr
  - Testing alignment (byte offset or length)  - is now a WordAnd

These element/byte length related calculations are encapsulated in
TypedArrayElementsInfo as struct methods.

This reduces the size of CreateTypedArray by 2.125 KB (24%) on Mac x64.release:
  - Before: 9,088
  - After:  6,896

This improves the performance of the following microbencmarks
  - TypedArrays-ConstructWithBuffer: ~87%
  - TypedArrays-SubarrayNoSpecies:   ~28%

Bug: v8:7161
Change-Id: I2239fd0e0af9d3ad55cd52318088d3c7c913ae44
Reviewed-on: https://chromium-review.googlesource.com/c/1456299
Commit-Queue: Peter Wong <peter.wm.wong@gmail.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59531}