[LexicalTextNode] Refactor: remove unnecessary type casting #234

Job	Run time
core-tests / integrity (20.11.0)	2m 16s
core-tests / unit (18.18.0)	1m 40s
core-tests / unit (18.18.0, beta)	1m 46s
e2e-tests / canary (macos-latest, 18.18.0, chromium, rich-text, modern-events) / e2e-test	11m 48s
	17m 30s

Provide feedback