[MERGE #3480 @jianchun] fix minor out of bound read (JavascriptString::ToInteger)
[MERGE #3480 @jianchun] fix minor out of bound read (JavascriptString::ToInteger)

Merge pull request #3480 from jianchun:readob

Reorder checks to avoid minor out of bound read.

Fix OS#13058871

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