Reland Don't assert rect mapping result if impossible

Reland Don't assert rect mapping result if impossible

The original CL was reverted because it broke some perf bots.
The reason is that the slow path misses ancestor overflow clipping
for some absolute-position object whose paint invalidation container
is under the absolute-position object's container.

This CL reland the original CL but doesn't enable
CHECK_FAST_PATH_SLOW_PATH_EQUALITY by default.

Avoid rect mapping result checking in the following cases:
- Any rect may contain saturated values;
- If a fixed-position ancestor disabled clipping.

BUG=591199
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_dbg,mac_blink_dbg,win_blink_dbg
TBR=chrishtr@chromium.org

Review-Url: https://codereview.chromium.org/1859833002
Cr-Commit-Position: refs/heads/master@{#390814}

Committed: https://crrev.com/0ddd48d1a4f271d3109019d55fe111a3220f1331
Cr-Commit-Position: refs/heads/master@{#391145}

[Xianzhu, 2016-05-02 21:43:06]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2016-05-02 21:43:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1936413002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1936413002/1

[commit-bot: I haz the power, 2016-05-03 01:30:28]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-05-03 01:32:14]

Description was changed from

==========
Reland Don't assert rect mapping result if impossible

The original CL was reverted because it broke some perf bots.
The reason is that the slow path misses ancestor overflow clipping
for some absolute-position object whose paint invalidation container
is under the absolute-position object's container.

This CL reland the original CL but doesn't enable
CHECK_FAST_PATH_SLOW_PATH_EQUALITY by default.

Avoid rect mapping result checking in the following cases:
- Any rect may contain saturated values;
- If a fixed-position ancestor disabled clipping.

BUG=591199
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_dbg,mac_blink_dbg,win_blink_dbg
TBR=chrishtr@chromium.org

Review-Url: https://codereview.chromium.org/1859833002
Cr-Commit-Position: refs/heads/master@{#390814}
==========

to

==========
Reland Don't assert rect mapping result if impossible

The original CL was reverted because it broke some perf bots.
The reason is that the slow path misses ancestor overflow clipping
for some absolute-position object whose paint invalidation container
is under the absolute-position object's container.

This CL reland the original CL but doesn't enable
CHECK_FAST_PATH_SLOW_PATH_EQUALITY by default.

Avoid rect mapping result checking in the following cases:
- Any rect may contain saturated values;
- If a fixed-position ancestor disabled clipping.

BUG=591199
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_dbg,mac_blink_dbg,win_blink_dbg
TBR=chrishtr@chromium.org

Review-Url: https://codereview.chromium.org/1859833002
Cr-Commit-Position: refs/heads/master@{#390814}

Committed: https://crrev.com/0ddd48d1a4f271d3109019d55fe111a3220f1331
Cr-Commit-Position: refs/heads/master@{#391145}
==========

[commit-bot: I haz the power, 2016-05-03 01:32:14]

Patchset 1 (id:??) landed as
https://crrev.com/0ddd48d1a4f271d3109019d55fe111a3220f1331
Cr-Commit-Position: refs/heads/master@{#391145}