Using Read/WriteLittleEndianValue method to access native
memory. This will perform byte reversal depending on the
endianness of the patform.

Testcase was added in CL: https://codereview.chromium.org/2405293002

R=ahaas@chromium.org, titzer@chromium.org
BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2479043003
Cr-Commit-Position: refs/heads/master@{#40815}