Supports :has() pseudo class matching

Add :has() pseudo class syntax support and matching logic behind a
runtime test feature (CSSPseudoHas)

<Syntax support>
Add syntax support for :has() pseudo class specified in Selectors 4.
 - https://www.w3.org/TR/selectors-4/#relational

:has() pseudo class takes a relatvie selector list as an argument.
 - :has(<relative-selector-list>)
 - <relative-selector-list> = <relative-selector>#
 - <relative-selector> = <combinator>? <complex-selector>

<relative-selector> is also specified in Selector 4, but it is not
supported yet.
 - https://www.w3.org/TR/selectors-4/#relative

So this CL only supports :has argument selectors starting with
descendant combinator. Argument selectors starting with other
combinators are not supported yet.
 - .a:has(.b)    : Supported
 - .a:has(> .b)  : Not supported yet
 - .a:has(~ .b)  : Not supported yet
 - .a:has(+ .b)  : Not supported yet

<Selector matching>
Add :has() pseudo class selector matching logic.

This CL suggests a stack-allocated :has() matching status cache
to prevent repetitive tree traversal and argument selector matching
operation.

The cache stores each element status as below.
 - Matched : Checked :has() and matched
 - Checked : Checked :has() but not matched
 - NotChecked : Not checked :has() (default)

This is the pseudo code of the matching operation for the :has
pseudo class with descendant relative argument selectors.
(e.g. ':has(.a)' or ':has(:scope .a)')

 ┬ Allocate cache on stack memory
 ├ Enter the style recalculation(or node selector API) sequence
 │  ├ ...
 │  ├ Enter the selector matching sequence
 │  │  ├ If matching :has pseudo class on an element
 │  │  │  └ Enter :has selector matching sequence
 │  │  │     ├ Get argument selector
 │  │  │     ├ Get element status from cache
 │  │  │     ├ If the element status is checked
 │  │  │     │  └ If the element status is matched
 │  │  │     │    └ Finish has pseudo class matching as matched
 │  │  │     ├ Else
 │  │  │     │  ├ Set the element status as checked
 │  │  │     │  └ Traverse all descendants of the element
 │  │  │     │    ├ Get the descendant status from cache
 │  │  │     │    ├ If the descendant status is checked
 │  │  │     │    │  └ If the descendant status is matched
 │  │  │     │    │    ├ Set the element status as matched
 │  │  │     │    │    └ Finish has pseudo class matching as matched
 │  │  │     │    └ Else
 │  │  │     │      ├ Set the descendant status as checked
 │  │  │     │      └ If the descendant matches the argument selector
 │  │  │     │        ├ Get start element of the shortest match
 │  │  │     │        ├ Traverse it's ancestors until met the element
 │  │  │     │        │  └ Set the ancestor status as matched
 │  │  │     │        ├ Set the element status as matched
 │  │  │     │        └ Finish has pseudo class matching as matched
 │  │  │     └ Finish has pseudo class matching as not matched
 │  │  └ Otherwise
 │  │     └ Do other selector matching sequence
 │  └ ...
 └ Release cache from stack memory

Other cases will be handled later in the separated CLs.
 - :has(> .a) or :has(:scope > .a)
 - :has(~ .a) or :has(:scope ~ .a)
 - :has(+ .a) or :has(:scope + .a)

This CL supports :has with the following javascript APIs.
 - querySelector
 - querySelectorAll
 - matches
 - closest

Changes in this CL were originally in the below 2 CLs. Those are
merged to prevent a web_test failure. (jquery/traversing.html)
 - https://chromium-review.googlesource.com/c/chromium/src/+/2648150
 - https://chromium-review.googlesource.com/c/chromium/src/+/2695192

Change-Id: I1992b70d86f47fc5f98437e1e6abea2da021ef6b
Bug: 669058
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2914717
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Byungwoo Lee <blee@igalia.com>
Cr-Commit-Position: refs/heads/master@{#888799}
21 files changed
tree: 1e9c2201e867e3ee0b68c7050c75848a21e97d18
  1. .clang-format
  2. .clang-tidy
  3. .eslintrc.js
  4. .git-blame-ignore-revs
  5. .gitattributes
  6. .gitignore
  7. .gn
  8. .mailmap
  9. .vpython
  10. .vpython3
  11. .yapfignore
  12. AUTHORS
  13. BUILD.gn
  14. CODE_OF_CONDUCT.md
  15. DEPS
  16. DIR_METADATA
  17. ENG_REVIEW_OWNERS
  18. LICENSE
  19. LICENSE.chromium_os
  20. OWNERS
  21. PRESUBMIT.py
  22. PRESUBMIT_test.py
  23. PRESUBMIT_test_mocks.py
  24. README.md
  25. WATCHLISTS
  26. android_webview/
  27. apps/
  28. ash/
  29. base/
  30. build/
  31. build_overrides/
  32. buildtools/
  33. cc/
  34. chrome/
  35. chromecast/
  36. chromeos/
  37. cloud_print/
  38. codelabs/
  39. codereview.settings
  40. components/
  41. content/
  42. courgette/
  43. crypto/
  44. dbus/
  45. device/
  46. docs/
  47. extensions/
  48. fuchsia/
  49. gin/
  50. google_apis/
  51. google_update/
  52. gpu/
  53. headless/
  54. infra/
  55. ios/
  56. ipc/
  57. jingle/
  58. media/
  59. mojo/
  60. native_client_sdk/
  61. net/
  62. pdf/
  63. ppapi/
  64. printing/
  65. remoting/
  66. rlz/
  67. sandbox/
  68. services/
  69. skia/
  70. sql/
  71. storage/
  72. styleguide/
  73. testing/
  74. third_party/
  75. tools/
  76. ui/
  77. url/
  78. weblayer/
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