port db2ba190 (r30634).

original commit message:

    The semantics of the %_CallFunction intrinsic seem to be very unclear,
    which resulted in a lot of bugs. Especially the combination with
    %IsSloppyModeFunction is always a bug, because the receiver would be
    wrapped in the wrong context. So the %IsSloppyModeFunction helper is
    gone now, and many of the buggy uses of %_CallFunction are also
    eliminated.

    If you ever need to call something with a different receiver, then
    %_Call is your friend now. It does what you want and implements the
    call sequence fully (and correct).

Review URL: https://codereview.chromium.org/1336443002

Cr-Commit-Position: refs/heads/master@{#30667}