Revert of deprecate non-phantom weak callbacks (patchset #1 id:1 of https://coderevie...

Revert of deprecate non-phantom weak callbacks (patchset #1 id:1 of https://codereview.chromium.org/1103173002/)

Reason for revert:
[Sheriff] Fails compilation on chromium android:
http://build.chromium.org/p/client.v8/builders/Android%20Builder/builds/4131

Is the chromium version our builder used maybe too old (it uses lkcr)? In that case please reland as soon as it's up-to-date.

Original issue's description:
> deprecate non-phantom weak callbacks
>
> BUG=
>
> Committed: https://crrev.com/39c31da2142ab0fca9dae279b9e59cd4951a1982
> Cr-Commit-Position: refs/heads/master@{#28077}

TBR=jochen@chromium.org,dcarney@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1104163002

Cr-Commit-Position: refs/heads/master@{#28079}