When we have a known JSTypedArray instance at optimization time, i.e. as
in asm.js-like use cases and also when there are global typed arrays that
are tracked via global object property constant tracking, we can generate
more efficient code in that case by specializing to the immutable internal
fields of the JSTypedArray (and the JSArrayBuffer backing it).

R=jarin@chromium.org
BUG=v8:4470,v8:5267

Review-Url: https://codereview.chromium.org/2510553002
Cr-Commit-Position: refs/heads/master@{#41017}