[ScrollUpdateOptimizations] Fix fixed-position overlap testing

1. Fall back to the generic cross-scroll overlap testing if there
   is any additional clip between the fixed-position state and the
   scroller overflow clip because the expanded fixed-position
   rect would be incorrectly clipped.
2. Also use CompositingReason::kFixedPosition for special fixed-
   position compositing reasons in a non-scrollable viewport, to
   use the fixed-position code path in overlap testing if possible
   to avoid extra overlaps.

Found the issues because the following tests failed with
ScrollUpdateOptimizations enabled by default:

external/wpt/css/css-multicol/fixedpos-static-pos-with-viewport-cb-001.html
external/wpt/css/css-multicol/fixedpos-static-pos-with-viewport-cb-002.html
external/wpt/css/css-multicol/fixedpos-static-pos-with-viewport-cb-003.html
external/wpt/css/css-position/position-fixed-scroll-overlap.html

I probably only checked blink_web_tests for failures when I tried the
original ScrollUpdateOptimizations CL with the feature enabled.

Bug: 1346789
Change-Id: Ia6fbcd72aebb355b1ba42f5c332a8e61a679ee66
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3838628
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1036822}
3 files changed
tree: 60be8da11f927801ed2498e3ece00255789606e6
  1. android_webview/
  2. apps/
  3. ash/
  4. base/
  5. build/
  6. build_overrides/
  7. buildtools/
  8. cc/
  9. chrome/
  10. chromecast/
  11. chromeos/
  12. codelabs/
  13. components/
  14. content/
  15. courgette/
  16. crypto/
  17. dbus/
  18. device/
  19. docs/
  20. extensions/
  21. fuchsia_web/
  22. gin/
  23. google_apis/
  24. google_update/
  25. gpu/
  26. headless/
  27. infra/
  28. ios/
  29. ipc/
  30. media/
  31. mojo/
  32. native_client_sdk/
  33. net/
  34. pdf/
  35. ppapi/
  36. printing/
  37. remoting/
  38. rlz/
  39. sandbox/
  40. services/
  41. skia/
  42. sql/
  43. storage/
  44. styleguide/
  45. testing/
  46. third_party/
  47. tools/
  48. ui/
  49. url/
  50. weblayer/
  51. .clang-format
  52. .clang-tidy
  53. .eslintrc.js
  54. .git-blame-ignore-revs
  55. .gitattributes
  56. .gitignore
  57. .gn
  58. .mailmap
  59. .rustfmt.toml
  60. .vpython
  61. .vpython3
  62. .yapfignore
  63. AUTHORS
  64. BUILD.gn
  65. CODE_OF_CONDUCT.md
  66. codereview.settings
  67. DEPS
  68. DIR_METADATA
  69. ENG_REVIEW_OWNERS
  70. LICENSE
  71. LICENSE.chromium_os
  72. OWNERS
  73. PRESUBMIT.py
  74. PRESUBMIT_test.py
  75. PRESUBMIT_test_mocks.py
  76. README.md
  77. WATCHLISTS
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