Port 79bcb454

Original Commit Message:

    This is a reland of a72b2f88
    Original change's description:
    > [arm] Restrict grouping pushes before a TailCall to registers only
    >
    > We optimize parallel moves performed before a TailCall by grouping adjacent
    > pushes. This way, we may use a single instruction to push multiple registers at
    > once. However, we also have support for pushing immediates and stack slots for
    > which the benefit is questionnable therefore this patch removes support for
    > them.
    >
    > Concerning immediate pushes, it looks like a mistake since we do not have
    > support for this case in `AssembleMove` so this patch removes it. Furthermore,
    > if we add a test for this case, we see that a `push ip` instruction is
    > generated, effectively pushing whatever was in `ip` at the time instead of
    > pushing a constant.
    >
    > Concerning stack slot pushes, we generate a more or less equivalent sequence of
    > instructions.
    >
    > Finally, grouping floating point pushes is not used anywhere so this patch
    > removes support for this also.
    >
    > Bug: v8:6553
    > Change-Id: I9b820d33361fc442dd813f66e1f96cda41009110
    > Reviewed-on: https://chromium-review.googlesource.com/567191
    > Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
    > Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
    > Cr-Commit-Position: refs/heads/master@{#46718}

R=pierre.langlois@arm.com, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: I8790c7a72f92803ea8fda3c6dc7e6b013e2e09e9
Reviewed-on: https://chromium-review.googlesource.com/588471Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Jaideep Bajwa <bjaideep@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#46949}