Bug 278928 – AX: AXTextOperation over multiple ranges is entirely broken

• Component: Accessibility
• Status: RESOLVED FIXED

[Samar Sunkaria]

When performing an AXTextOperation over multiple ranges (_in descending order of their position_), typically only the first range is replaced. In a contenteditable, multiple ranges might be replaced correctly if they aren’t located within the same node.

This problem is consistently reproducible. However, it is much harder (though not impossible) to reproduce when a non-smart replacement is performed (as proposed in https://bugs.webkit.org/show_bug.cgi?id=278458).

This seems to happen whenever the replacement isn't executed using the `ReplaceSelectionCommand::performTrivialReplace` and instead takes the longer path in `ReplaceSelectionCommand::doApply`. While the initial replacement is performed correctly, subsequent replacements fail because text selection fails on the following iteration of `AccessibilityObject::performTextOperation`.

After the first replacement the SimpleRanges stored in `AccessibilityTextOperation` are orphaned, and can no longer be used for performing a selection; ever since https://bugs.webkit.org/show_bug.cgi?id=221942 was introduced. That change likely caused this bug.

[Radar WebKit Bug Importer]

<rdar://problem/135021789>

[Samar Sunkaria]

In particular I am hitting the ASSERT_NOT_REACHED() for an orphaned selection in FrameSelection::setSelectionWithoutUpdatingAppearance, for the second selection range in the same node as a previous replacement. 

```
        if (newSelection.isOrphan()) {
            ASSERT_NOT_REACHED();
            clear();
            return false;
        }
```

[Samar Sunkaria]

Pull request: https://github.com/WebKit/WebKit/pull/34534

[EWS]

Committed 284801@main (4b8b62af6ff6): <https://commits.webkit.org/284801@main>

Reviewed commits have been landed. Closing PR #34534 and removing active labels.

[EWS]

Committed 283286.232@safari-7620-branch (6f342184a21d): <https://commits.webkit.org/283286.232@safari-7620-branch>

Reviewed commits have been landed. Closing PR #1992 and removing active labels.