Remove natives_blob.bin's arch dependence.

This is first patch which keeps renaming logical in gn, but didn't rename natives_blob.bin to arch specific name, so the v8 patch (https://codereview.chromium.org/2074283002/) could be landed afterwards without breaking anything.

BUG=620855

Review-Url: https://codereview.chromium.org/2075283003
Cr-Commit-Position: refs/heads/master@{#401005}
7 files changed