PPC: [calls] Consistent call protocol for calls.

PPC: [calls] Consistent call protocol for calls.

Port b37907ff7f866873ddfbfc97670b43c19a5fc7f9

Original commit message:
    The number of actual arguments should always be available, there's no
    point in trying to optimize away a simple assignment of an immediate to
    a register before some calls.

    The main motivation is to have a consistent state at the beginning of every
    function. Currently the arguments register (i.e. rax or eax) either contains
    the number of arguments or some random garbage depending on whether
    the callsite decided that the callee might need the information or not.
    This causes trouble with runtime implementations of functions that
    do not set internal_formal_parameter_count to the DontAdaptArguments
    sentinel (we don't have any of those yet), but also makes it impossible
    to sanity check the arguments in the callee, because the callee doesn't
    know whether the caller decided to pass the number of arguments or
    random garbage.

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=v8:4413
LOG=n

Committed: https://crrev.com/422b0fa72de7516e82d2ce498a1b483da939cef7
Cr-Commit-Position: refs/heads/master@{#30662}

[dstence, 2015-09-09 15:46:30]

lgtm

[MTBrandyberry, 2015-09-09 15:46:44]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-09-09 15:46:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1314353007/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1314353007/20001

[commit-bot: I haz the power, 2015-09-09 16:09:24]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-09 16:09:33]

Patchset 2 (id:??) landed as
https://crrev.com/422b0fa72de7516e82d2ce498a1b483da939cef7
Cr-Commit-Position: refs/heads/master@{#30662}