stagent.dev: Clicking email field on sign up form does not allow input until you click a second time

[pxlcoder]

f3b946f

stagent.dev: Clicking email field on sign up form does not allow input until you click a second time
https://bugs.webkit.org/show_bug.cgi?id=245976
rdar://98341809

Reviewed by Ryosuke Niwa.

Safari's AutoFill heuristic recently began (correctly) detecting email fields
on stagent.dev as autofillable. Consequently, Safari now adds an autofill
button to their email field when it is clicked.

WebKit has a longstanding bug where the selection is lost when an input
decoration is added while the selection is inside the input. Adding a decoration,
such as the autofill button, changes the structure of the shadow subtree.
Specifically, the contenteditable element is removed from the shadow root and
added to a separate container. The removal of the contenteditable element wipes
out the selection. To work around this issue, Safari has logic to restore the
selection after adding an autofill button.

However, Safari's workaround is not robust, as the HTML spec limits which input
types support the input selection APIs, such as `setSelectionStart` and
`setSelectionEnd`. Email inputs do not support the selection API, hence Safari's
workaround fails to apply to email fields where an autofill button is added.

To fix, restore the selection in WebKit, following the addition of an input
decoration, such as the autofill button. Note that this change still results in
two "selectionchange" events getting dispatched when focusing an autofillable
field for the first time. However, this matches behavior in shipping Safari.

An alternate solution considered was to avoid moving the contenteditable element
when adding a decoration. However, this change would have a much larger surface
area, and is too risky in the short term.

* LayoutTests/fast/forms/auto-fill-button/show-auto-fill-button-while-selection-inside-field-expected.txt: Added.
* LayoutTests/fast/forms/auto-fill-button/show-auto-fill-button-while-selection-inside-field.html: Added.
* Source/WebCore/html/HTMLTextFormControlElement.h:

Expose a method returning the enumerated value of the selection direction so
that the variant of `setSelectionRange` that does not dispatch "select" events
can be used.

* Source/WebCore/html/TextFieldInputType.cpp:
(WebCore::TextFieldInputType::createContainer):

Restore the selection after an input decoration is added.

Canonical link: https://commits.webkit.org/255229@main

c221a57

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 🧪 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-debug	✅ 🛠 gtk	✅ 🛠 wincairo
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🛠 mac-AS-debug	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 api-mac	✅ 🧪 api-gtk
	✅ 🛠 tv	✅ 🧪 mac-wk1
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2
✅ 🛠 🧪 merge	✅ 🛠 watch	❌ 🧪 mac-AS-debug-wk2
	✅ 🛠 watch-sim	✅ 🧪 mac-wk2-stress

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 6160508)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	❌ 🛠 🧪 win
✅ 🧪 bindings	✅ 🛠 ios-sim	⏳ 🛠 mac-debug	✅ 🛠 gtk	✅ 🛠 wincairo
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	✅ 🛠 mac-AS-debug	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	🧪 api-mac	❌ 🧪 api-gtk
	✅ 🛠 tv	❌ 🧪 mac-wk1
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2
	✅ 🛠 watch	❌ 🧪 mac-AS-debug-wk2
	✅ 🛠 watch-sim	✅ 🧪 mac-wk2-stress

[rniwa]

r=me

[pxlcoder]

Thanks for the review!

Updated the test to work on iOS.

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 4786e36)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	❌ 🛠 🧪 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-debug	✅ 🛠 gtk	✅ 🛠 wincairo
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🛠 mac-AS-debug	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	🧪 api-mac	✅ 🧪 api-gtk
	✅ 🛠 tv	❌ 🧪 mac-wk1
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2
	✅ 🛠 watch	❌ 🧪 mac-AS-debug-wk2
	✅ 🛠 watch-sim	✅ 🧪 mac-wk2-stress

[webkit-early-warning-system]

EWS run on current version of this PR (hash c221a57)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 🧪 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-debug	✅ 🛠 gtk	✅ 🛠 wincairo
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🛠 mac-AS-debug	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 api-mac	✅ 🧪 api-gtk
	✅ 🛠 tv	✅ 🧪 mac-wk1
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2
✅ 🛠 🧪 merge	✅ 🛠 watch	❌ 🧪 mac-AS-debug-wk2
	✅ 🛠 watch-sim	✅ 🧪 mac-wk2-stress

[webkit-commit-queue]

Committed 255229@main (f3b946f): https://commits.webkit.org/255229@main

Reviewed commits have been landed. Closing PR #4950 and removing active labels.