QuillToolbarSelectLineHeightStyleDropdownButton ignores defaultDisplayText

[d-ukhanov]

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Flutter Quill Version

11.5.0

Steps to Reproduce

1. Add QuillSimpleToolbar with showLineHeightButton: true and set defaultDisplayText in QuillToolbarSelectLineHeightStyleDropdownButtonOptions.
2. Use an empty document (no line-height attribute), type and select text.

Expected results

When no line-height attribute is present, the button label shows the provided defaultDisplayText.

Actual results

Label shows 1 (“Normal”); defaultDisplayText is ignored.

Additional Context

Suggested Fix

If attribute.value == null, prefer options.defaultDisplayText before falling back to "Normal".