Fix memory leak in WTF-8 string intern
Fix memory leak in WTF-8 string intern

Affected large strings.

svaarala/duktape,svaarala/duktape,svaarala/duktape,svaarala/duktape,svaarala/duktape,svaarala/duktape,svaarala/duktape,svaarala/duktape,svaarala/duktape