Save functionBody->GetConstantCount() in local var
Save functionBody->GetConstantCount() in local var

Avoids repeated calls to this method, which I hope will allow OACR to
conclude that the arithmetic and array index on line 53 is safe.

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