Make TextRun::isolatedCopy copy character data in more cases

https://bugs.webkit.org/show_bug.cgi?id=241581

Reviewed by Simon Fraser.

* Source/WebCore/platform/graphics/TextRun.h:
(WebCore::TextRun::isolatedCopy const):

Canonical link: https://commits.webkit.org/251521@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@295516 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/platform/graphics/TextRun.h

@@ -184,8 +184,10 @@ inline void TextRun::setTabSize(bool allow, const TabSize& size)
 inline TextRun TextRun::isolatedCopy() const
 {
     TextRun clone = *this;
-    if (m_text.impl() && m_text.impl()->isExternal())
-        clone.m_text = m_text.isolatedCopy();
+    if (clone.m_text.is8Bit())
+        clone.m_text = String(clone.m_text.characters8(), clone.m_text.length());
+    else
+        clone.m_text = String(clone.m_text.characters16(), clone.m_text.length());
     return clone;
 }