Unreviewed, reverting 269819@main.

https://bugs.webkit.org/show_bug.cgi?id=263781

It didn't fix the Speedometer regression

Reverted changeset:

"Unreviewed partial revert of 269630@main to address Speedometer regression"
https://bugs.webkit.org/show_bug.cgi?id=263730
https://commits.webkit.org/269819@main

Canonical link: https://commits.webkit.org/269849@main

Source/WTF/wtf/text/StringView.h

@@ -561,15 +561,15 @@ inline StringView StringView::substring(unsigned start, unsigned length) const
 
 inline UChar StringView::characterAt(unsigned index) const
 {
-    ASSERT_WITH_SECURITY_IMPLICATION(index < length());
+    RELEASE_ASSERT(index < length());
     if (is8Bit())
         return characters8()[index];
     return characters16()[index];
 }
 
 inline UChar StringView::unsafeCharacterAt(unsigned index) const
 {
-    ASSERT_WITH_SECURITY_IMPLICATION(index < length());
+    ASSERT(index < length());
     if (is8Bit())
         return characters8()[index];
     return characters16()[index];