Fixed some linter issues in typed_arrays_test.js.
Added v8::Platform initialization, required by v8 3.29.

I don't actually have a version of v8 3.29 installed on my workstation
to test with for the open source release, so doing this commit on a
branch to start with. It is necessary for use with the Google-internal
version.
Added two missing includes for v8's libplatform.h.