[MERGE #4121 @sigatrev] use param count as int32
[MERGE #4121 @sigatrev] use param count as int32

Merge pull request #4121 from sigatrev:loadParamCount

all MD LoadInputParamCount methods use TyMachReg. Most use locations expect TyMachReg, but GenerateFastArgumentsLdElemI uses it to compare with a TyInt32.

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