…mPoint"

This reverts commit dd944882a245a5117b50cb417138d92f32d931d6.

Reason for revert:
This causes WebKit Linux Trusty ASAN buildbot failure.
https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Linux%20Trusty%20ASAN/builds/8618

23:46:29.565 3877   ==1==ERROR: AddressSanitizer: use-after-poison on address 0x7ead60c0dbf0 at pc 0x00000dca937a bp 0x7ffd86b90c10 sp 0x7ffd86b90c08
23:46:29.565 3877   READ of size 8 at 0x7ead60c0dbf0 thread T0 (content_shell)
23:46:29.565 3877       #0 0xdca9379 in operator==<const blink::TreeScope, const blink::TreeScope> third_party/WebKit/Source/platform/heap/Member.h:128:27
23:46:29.565 3877       #1 0xdca9379 in blink::TreeScope::Retarget(blink::Element const&) const third_party/WebKit/Source/core/dom/TreeScope.cpp:393:0
23:46:29.565 3877       #2 0xdca8894 in blink::TreeScope::HitTestPointInternal(blink::Node*) const third_party/WebKit/Source/core/dom/TreeScope.cpp:267:10
23:46:29.565 3877       #3 0xdca8325 in HitTestPoint third_party/WebKit/Source/core/dom/TreeScope.cpp:254:10
23:46:29.566 3877       #4 0xdca8325 in blink::TreeScope::ElementFromPoint(double, double) const third_party/WebKit/Source/core/dom/TreeScope.cpp:245:0
23:46:29.566 3877       #5 0xc9353a7 in elementFromPoint third_party/WebKit/Source/core/dom/DocumentOrShadowRoot.h:38:23

Original change's description:
> Fix retargeting of result in elementFromPoint and elementsFromPoint
>
> Currently elementFromPoint and elementsFromPoint are not per spec, and it may
> return null incorrectly. This change adds retargeting of the result with
> respect to the context object, and adds some tests that are similar to
> elementFromPoint tests in WebKit, but with some corrected cases:
> https://git.webkit.org/?p=WebKit-https.git;a=blob;f=LayoutTests/fast/shadow-dom/DocumentOrShadowRoot-prototype-elementFromPoint.html;h=a8dc4da2430713521b9ba77c742db10397a8e638;hb=HEAD
>
> Spec:
> https://w3c.github.io/webcomponents/spec/shadow/#extensions-to-the-documentorshadowroot-mixin
>
> Bug: 759947
> Change-Id: I6aece5e9cc826124772c6ce13c806865055b2b9b
> Reviewed-on: https://chromium-review.googlesource.com/808446
> Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
> Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
> Reviewed-by: Hayato Ito <hayato@chromium.org>
> Reviewed-by: Takayoshi Kochi <kochi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#531139}

TBR=kochi@chromium.org,dgozman@chromium.org,hayato@chromium.org,pfeldman@chromium.org,rakina@chromium.org

Change-Id: Id62abd371d93627d3178b63ca189cecfe9ff44d4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 759947
Reviewed-on: https://chromium-review.googlesource.com/880264
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#531178}

chromedriver doesn't allow changing Object.prototype to add enumerable
properties, but this test requires setting some values on
Object.prototype.  When Object.prototype.a is set to:

  {b: {c: 'on proto'}}

chromedriver fails with:

    JavascriptErrorException: javascript error (500): Maximum call stack size exceeded
      (Session info: chrome=72.0.3626.121)

    Remote-end stacktrace:

    #0 0x563ff3a32a59 <unknown>
    #1 0x563ff39cb7f3 <unknown>
    #2 0x563ff38fcd7c <unknown>
    #3 0x563ff38ff78c <unknown>
    #4 0x563ff38ff5f7 <unknown>
    #5 0x563ff38ffbe7 <unknown>
    #6 0x563ff38fff1b <unknown>
    #7 0x563ff38a3f7a <unknown>
    #8 0x563ff3899bf2 <unknown>
    #9 0x563ff38a37b7 <unknown>
    #10 0x563ff3899ac3 <unknown>
    #11 0x563ff38782d2 <unknown>
    #12 0x563ff3879112 <unknown>
    #13 0x563ff39fe865 <unknown>
    #14 0x563ff39ff32b <unknown>
    #15 0x563ff39ff70c <unknown>
    #16 0x563ff39d940a <unknown>
    #17 0x563ff39ff997 <unknown>
    #18 0x563ff39e9947 <unknown>
    #19 0x563ff3a1a800 <unknown>
    #20 0x563ff3a3c8be <unknown>
    #21 0x7f3bf4545494 start_thread
    #22 0x7f3bf2d58a8f clone

    Ran 1 tests finished in 2.0 seconds.
      • 0 ran as expected. 0 tests skipped.
      • 1 tests had errors unexpectedly

Work around this problem by cleaning up the test environment so
Object.prototype no longer has the override by the time chromedriver
tries to inspect the test result.

While here, fix the other tests to use the t.add_cleanup() function
so they'll cleanup their test environment in case they exit in
some other way besides reaching t.done().

The underlying chromedriver issue is tracked upstream at
https://crbug.com/chromedriver/2555.

Bug: 934844
Change-Id: Id1b4ab2a908bfbc001e2a2d045eeec3ef01c24d9

This reverts commit 712c3cf3ed8201420acf23f760eaa34be20781cd.

Reason for revert: This patch causes webkit-layout-tests failure on WebKit_Linux_Trusty_ASAN bot:
https://ci.chromium.org/p/chromium/builders/ci/WebKit%20Linux%20Trusty%20ASAN/25720

Unexpected Failures:
* external/wpt/css/css-scroll-snap/scroll-snap-type.html
* virtual/threaded/external/wpt/css/css-scroll-snap/scroll-snap-type.html

STDERR: ==1==ERROR: AddressSanitizer: heap-use-after-free on address 0x61200023f8d8 at pc 0x5620c924e56d bp 0x7ffde3c56830 sp 0x7ffde3c56828
STDERR: READ of size 8 at 0x61200023f8d8 thread T0 (content_shell)
STDERR:     #0 0x5620c924e56c in get ./../../base/memory/scoped_refptr.h:212:27
STDERR:     #1 0x5620c924e56c in Style ./../../third_party/blink/renderer/core/layout/layout_object.h:1615:0
STDERR:     #2 0x5620c924e56c in GetPhysicalSnapType ./../../third_party/blink/renderer/core/page/scrolling/snap_coordinator.cc:88:0
STDERR:     #3 0x5620c924e56c in blink::SnapCoordinator::UpdateSnapContainerData(blink::LayoutBox&) ./../../third_party/blink/renderer/core/page/scrolling/snap_coordinator.cc:107:0
STDERR:     #4 0x5620c924e74b in blink::SnapCoordinator::UpdateAllSnapContainerData() ./../../third_party/blink/renderer/core/page/scrolling/snap_coordinator.cc:76:5

Original change's description:
> Correctly handle scroll-snap-type changes to 'none'
>
>
> Previously when a scroll container's snap type is changed to 'none' its
> data was discarded including all of its snap areas. However this is
> incorrect. Because while the snap type is 'none', the element is still
> a scroll container which per spec [1] means  that is should continue to
> captures the snap areas in its subtree for whom it is the nearest
> ancestor scroll container . The only difference is that it no longer
> snaps.
>
> The fix is that we no longer remove the snap container data just
> because is has a 'none' snap type and instead keep it and its snap
> areas. But we check the snap type before performing any snap.
>
> To ensure this does not introduce any performance regression, this CL
> also includes an optimization where we avoid re-calculating
> snap_container_data when the snap type is 'none'. So keeping these snap
> data should not be cheap.
>
> Note that there is another problem where if the current snap container
> is no longer a scroll container (e.g., overflow: scroll => overflow:
> visible) we release its snap areas and they become "orphan". But if we
> are to do this correctly, we should re-assign these areas to the next
> stroller in the chain. Similarly when an element becomes a scroll
> container, it can potentially take over snap areas from its parent snap
> container.
>
>
> This patch does not address that situation yet but fixes the easier
> problem.
>
> [1] https://drafts.csswg.org/css-scroll-snap/#overview
>
> Bug: 953575
> Test:
>  - wpt/css/css-scroll-snap/scroll-snap-type-change.html => Changing snap-type should work correctly
>  - wpt/css/css-scroll-snap/scroll-snap-type.html => Add a specific test for type 'none' to ensure it does not snap
>
> Change-Id: Ie493ad68ecba818ed41c0ee103ccf44725ff6e3f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1589899
> Reviewed-by: Majid Valipour <majidvp@chromium.org>
> Reviewed-by: David Bokan <bokan@chromium.org>
> Commit-Queue: Majid Valipour <majidvp@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#657460}

TBR=bokan@chromium.org,majidvp@chromium.org

Change-Id: I3a327f6e342e95d045194d24ceaf49de52b2b921
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 953575
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1600437
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#657571}