[MERGE #4528 @leirocks] Fix bad assertion in DirectSetItemAtRange for OP_MEMSET
[MERGE #4528 @leirocks] Fix bad assertion in DirectSetItemAtRange for OP_MEMSET

Merge pull request #4528 from leirocks:op_memset

mrkmarron/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore