A64: Handle a few TODOs.

A64: Handle a few TODOs.

Notes about a few TODOs handled in this patch:

* In ProfileEntryHookStub::Generate:
    Stubs are always called with relocation.

* In CreateArrayDispatchOneArgument:
    The branches to registers can't be conditional. We could use a jump table, but
    there are only 6 different kinds so it is likely not worth it.

* In Builtins::Generate_StringConstructCode:
    Rename the argc register (x0) after its meaning changes.
    Remove a TODO: using a macro would not make the code clearer.

* In Generate_JSEntryTrampolineHelper:
    Remove the TODO and raise an internal issue to investigate this.

* In Disassembler::SubstituteBranchTargetField:
    Print the target address, but we don't have more info on the target.

R=ulan@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=19724

[ulan, 2014-03-04 09:46:00]

lgtm

[Alexandre Rames, 2014-03-07 15:20:40]

Committed patchset #1 manually as r19724 (presubmit successful).