Reland: WTF: Implement explicit RefPtr::operator bool.

Reland: WTF: Implement explicit RefPtr::operator bool.

This is the modern alternative to the "safe bool" idiom. Some changes at
call sites are required, primarily because returning a boolean does not
cause an explicit conversion.

This is a reland of https://codereview.chromium.org/1891473002/ with no changes
aside from a rebase. There should be no more performance impact after the fix
in bug 607208.

BUG=607208
Committed: https://crrev.com/70843029b30a2566640848f072312cde61954ed3
Cr-Commit-Position: refs/heads/master@{#399979}

[jbroman, 2016-06-15 13:58:07]

Description was changed from

==========
WTF: Implement explicit RefPtr::operator bool.

This is the modern alternative to the "safe bool" idiom. Some changes at
call sites are required, primarily because returning a boolean does not
cause an explicit conversion.

This is a reland of https://codereview.chromium.org/1891473002/ with no changes
aside from a rebase. There should be no more performance impact after the fix
in bug 607208.

BUG=607208
==========

to

==========
Reland: WTF: Implement explicit RefPtr::operator bool.

This is the modern alternative to the "safe bool" idiom. Some changes at
call sites are required, primarily because returning a boolean does not
cause an explicit conversion.

This is a reland of https://codereview.chromium.org/1891473002/ with no changes
aside from a rebase. There should be no more performance impact after the fix
in bug 607208.

BUG=607208
==========

[jbroman, 2016-06-15 13:59:55]

jbroman@chromium.org changed reviewers:
+ thakis@chromium.org

[jbroman, 2016-06-15 13:59:56]

OK, the memchr CL seems to be sticking now (knock on wood), so I'd like to try
to land this again.

The previous regression has gone away, so this should have no specific perf
impact (though my N4 in WAT seems to think it somehow manages to improve some
blink_perf.dom results). And the perf trybots aren't working for me right now.

[Nico, 2016-06-15 14:02:31]

lgtm

(i checked if "Recommendations for explicit conversion operator call-sites" on
chromium-dev had any conclusion…doesn't look like it)

[jbroman, 2016-06-15 14:27:51]

The CQ bit was checked by jbroman@chromium.org

[commit-bot: I haz the power, 2016-06-15 14:28:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2063773002/1

[commit-bot: I haz the power, 2016-06-15 18:55:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-06-15 18:55:21]

CQ bit was unchecked

[commit-bot: I haz the power, 2016-06-15 18:57:01]

Description was changed from

==========
Reland: WTF: Implement explicit RefPtr::operator bool.

This is the modern alternative to the "safe bool" idiom. Some changes at
call sites are required, primarily because returning a boolean does not
cause an explicit conversion.

This is a reland of https://codereview.chromium.org/1891473002/ with no changes
aside from a rebase. There should be no more performance impact after the fix
in bug 607208.

BUG=607208
==========

to

==========
Reland: WTF: Implement explicit RefPtr::operator bool.

This is the modern alternative to the "safe bool" idiom. Some changes at
call sites are required, primarily because returning a boolean does not
cause an explicit conversion.

This is a reland of https://codereview.chromium.org/1891473002/ with no changes
aside from a rebase. There should be no more performance impact after the fix
in bug 607208.

BUG=607208

Committed: https://crrev.com/70843029b30a2566640848f072312cde61954ed3
Cr-Commit-Position: refs/heads/master@{#399979}
==========

[commit-bot: I haz the power, 2016-06-15 18:57:03]

Patchset 1 (id:??) landed as
https://crrev.com/70843029b30a2566640848f072312cde61954ed3
Cr-Commit-Position: refs/heads/master@{#399979}