Need to report error when use constant which has offset bigger than root constant size.

[python3kgae]

cbuffer cb : register(b0) { float a; float b; }

[RootSignature("RootFlags(0), RootConstants(b0, num32BitConstants = 1)")] float main() : SV_Target { return b; }

Root constant size is 1, but b has offset 1 which is out of bound.