X87: Use platform specific stubs for vector-based Load/KeyedLoad.
X87: Use platform specific stubs for vector-based Load/KeyedLoad.

port 34a1a76ddf30109f7b6cb60aa2651493ab38660a (r27235)

original commit message:

  A hydrogen code stub is not the best approach because it builds a frame
  and doesn't have the technology to discard roots at tail call exits.
  Platform-specific stubs provide much better performance at this point.

BUG=

Review URL: https://codereview.chromium.org/1025073005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#27394}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh