Revert of Optimize the pre-paint tree walk and ClipRects

Revert of Optimize the pre-paint tree walk and ClipRects (patchset #3 id:40001 of https://codereview.chromium.org/2784963002/ )

Reason for revert:
On further investigation, found that this patch introduces too much inefficiency by
making all PaintLayers pay the cost of a ClipRects object, rather than just ones that
induce subsequences.

Original issue's description:
> Optimize the pre-paint tree walk and ClipRects.
> 
> 1. Avoid malloc for ClipRects objects. This trades reduced malloc for
> a somewhat larger PaintLayer.
> 2. Get rid of now-unnecessary logic to check clipping ancestors (GeomteryMapper
> now checks for transforms on infininte rects instead).
> 3. ALWAYS_INLINE on some helper methods of PrePaintTreeWalk.
> 
> Local runs showed pre-paint time improvements in about:tracing for
> Paint/containment-resize.html of up to 5%.
> 
> I am also running a CT analysis with and without SPInvalidation on to see effect
> on paint times. Early data suggests no strong change either way. (though note that
> this CL is mainly aimed at reducing time in pre-paint).
> 
> BUG=692614
> CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
> 
> Review-Url: https://codereview.chromium.org/2784963002
> Cr-Commit-Position: refs/heads/master@{#460808}
> Committed: https://chromium.googlesource.com/chromium/src/+/65b5d60ab86950a42ade9f0aee9e5e67d8c3ff20

TBR=pdr@chromium.org,wangxianzhu@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=692614

[chrishtr, 2017-04-02 17:02:43]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2017-04-02 17:02:43]

Created Revert of Optimize the pre-paint tree walk and ClipRects

[commit-bot: I haz the power, 2017-04-02 17:02:48]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-02 18:30:23]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1491152563110000, "parent_rev":
"726c89662647e7699554827c170d88f7f0543606", "commit_rev":
"e51c85fe536c1a2810a6a08904c08935b7020e5f"}

[commit-bot: I haz the power, 2017-04-02 18:36:39]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-04-02 18:36:39]

Prior attempt to commit was detected, but we were not able to check whether the
issue was successfully committed. Please check Git history manually and re-check
CQ or close this issue as needed.