Block Editor: Skip focusTabbable if no active element

[aduth]

Fixes #21276

This pull request seeks to resolve an error which occurs in Internet Explorer when pressing Enter whilst a block is selected in Select interaction mode.

For full debugging details, see comment at #21276 (comment) .

Implementation notes:

The changes as proposed follow the second of the two proposed fixes from #21276 (comment) .

Testing Instructions:

Repeat Steps to Reproduce from #21276, verifying that no crash occurs in Internet Explorer.

[youknowriad]

I also fixed a recent issue on focusTabbable recently. While doing so I was thinking that actually focusTabbable might not be needed anymore (or at least the logic to find the textual elements) as we refactor all textual blocks to use the light block DOM wrapper (it might still be needed for BC)

[github-actions]

Size Change: +4 B (0%)

Total Size: 884 kB

Filename	Size	Change
build/block-editor/index.js	102 kB	+4 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
build/a11y/index.js	1.02 kB	0 B
build/annotations/index.js	3.45 kB	0 B
build/api-fetch/index.js	3.8 kB	0 B
build/autop/index.js	2.59 kB	0 B
build/blob/index.js	620 B	0 B
build/block-directory/index.js	6.03 kB	0 B
build/block-directory/style-rtl.css	760 B	0 B
build/block-directory/style.css	760 B	0 B
build/block-editor/style-rtl.css	10.7 kB	0 B
build/block-editor/style.css	10.7 kB	0 B
build/block-library/editor-rtl.css	7.22 kB	0 B
build/block-library/editor.css	7.22 kB	0 B
build/block-library/index.js	110 kB	0 B
build/block-library/style-rtl.css	7.53 kB	0 B
build/block-library/style.css	7.54 kB	0 B
build/block-library/theme-rtl.css	669 B	0 B
build/block-library/theme.css	671 B	0 B
build/block-serialization-default-parser/index.js	1.65 kB	0 B
build/block-serialization-spec-parser/index.js	3.1 kB	0 B
build/blocks/index.js	57.5 kB	0 B
build/components/index.js	195 kB	0 B
build/components/style-rtl.css	16.6 kB	0 B
build/components/style.css	16.5 kB	0 B
build/compose/index.js	6.21 kB	0 B
build/core-data/index.js	10.7 kB	0 B
build/data-controls/index.js	1.03 kB	0 B
build/data/index.js	8.23 kB	0 B
build/date/index.js	5.37 kB	0 B
build/deprecated/index.js	772 B	0 B
build/dom-ready/index.js	569 B	0 B
build/dom/index.js	3.05 kB	0 B
build/edit-navigation/index.js	2.48 kB	0 B
build/edit-navigation/style-rtl.css	239 B	0 B
build/edit-navigation/style.css	241 B	0 B
build/edit-post/index.js	92.3 kB	0 B
build/edit-post/style-rtl.css	12 kB	0 B
build/edit-post/style.css	12 kB	0 B
build/edit-site/index.js	9.12 kB	0 B
build/edit-site/style-rtl.css	4.61 kB	0 B
build/edit-site/style.css	4.61 kB	0 B
build/edit-widgets/index.js	4.43 kB	0 B
build/edit-widgets/style-rtl.css	3.74 kB	0 B
build/edit-widgets/style.css	3.74 kB	0 B
build/editor/editor-styles-rtl.css	423 B	0 B
build/editor/editor-styles.css	426 B	0 B
build/editor/index.js	42.8 kB	0 B
build/editor/style-rtl.css	3.49 kB	0 B
build/editor/style.css	3.49 kB	0 B
build/element/index.js	4.44 kB	0 B
build/escape-html/index.js	733 B	0 B
build/format-library/index.js	6.95 kB	0 B
build/format-library/style-rtl.css	502 B	0 B
build/format-library/style.css	502 B	0 B
build/hooks/index.js	1.93 kB	0 B
build/html-entities/index.js	622 B	0 B
build/i18n/index.js	3.57 kB	0 B
build/is-shallow-equal/index.js	710 B	0 B
build/keyboard-shortcuts/index.js	2.3 kB	0 B
build/keycodes/index.js	1.7 kB	0 B
build/list-reusable-blocks/index.js	2.99 kB	0 B
build/list-reusable-blocks/style-rtl.css	226 B	0 B
build/list-reusable-blocks/style.css	226 B	0 B
build/media-utils/index.js	4.84 kB	0 B
build/notices/index.js	1.57 kB	0 B
build/nux/index.js	3.01 kB	0 B
build/nux/style-rtl.css	616 B	0 B
build/nux/style.css	613 B	0 B
build/plugins/index.js	2.54 kB	0 B
build/primitives/index.js	1.5 kB	0 B
build/priority-queue/index.js	780 B	0 B
build/redux-routine/index.js	2.84 kB	0 B
build/rich-text/index.js	14.5 kB	0 B
build/server-side-render/index.js	2.54 kB	0 B
build/shortcode/index.js	1.69 kB	0 B
build/token-list/index.js	1.28 kB	0 B
build/url/index.js	4.01 kB	0 B
build/viewport/index.js	1.6 kB	0 B
build/warning/index.js	1.14 kB	0 B
build/wordcount/index.js	1.17 kB	0 B

_{compressed-size-action}

[youknowriad]

Code looks good. I'm not in capacity to test this in IE11 but I'm confident about the changes.

[aduth]

I also fixed a recent issue on focusTabbable recently. While doing so I was thinking that actually focusTabbable might not be needed anymore (or at least the logic to find the textual elements) as we refactor all textual blocks to use the light block DOM wrapper (it might still be needed for BC)

Would that depend on the block, based on what its root element is? A quote block, for example, would have multiple focusable fields, none of which are the root element (<p> or <cite> within <blockquote>). Won't that still need focusTabbable?

In any case, as you mention, since there always will third-party blocks relying on the current behavior, I think it will need to stick around in one form or another.

[youknowriad]

@aduth Right :) I thought about whether using inner blocks for Quote would fix but it's not even the case, we might even need to surface it as an API (opt-in or opt-out) as I can image that some container blocks would want to focus their first textual inner blocks in some cases.