Fix String.fromCharCode() behavior for std variant
Fix String.fromCharCode() behavior for std variant

The non-standard (default) variant allows non-BMP codepoints which get
encoded as extended UTF-8.  The standard variant should use ToUint16()
coercion so that e.g. 0x123456 emits 0x3456.

The previous (buggy) code used ToUint32() + CESU-8 encoding in that case
which caused two codepoints (CESU-8) to be emitted for a codepoint (this
would actually be correct behavior for String.fromCodePoint()).

Fix the bug by using ToUint16() coercion when the standard behavior is
enabled.

harold-b/duktape,svaarala/duktape,svaarala/duktape,markand/duktape,harold-b/duktape,markand/duktape,markand/duktape,svaarala/duktape,svaarala/duktape,jmptrader/duktape,svaarala/duktape,markand/duktape,harold-b/duktape,jmptrader/duktape,markand/duktape,svaarala/duktape,jmptrader/duktape,jmptrader/duktape,jmptrader/duktape,harold-b/duktape,svaarala/duktape,jmptrader/duktape,jmptrader/duktape,markand/duktape,harold-b/duktape,markand/duktape,markand/duktape,jmptrader/duktape,harold-b/duktape,harold-b/duktape,svaarala/duktape,jmptrader/duktape,markand/duktape,markand/duktape,jmptrader/duktape,harold-b/duktape,harold-b/duktape,svaarala/duktape,harold-b/duktape