Missing a validateInteger check

We can build much smaller Mono runtime for .NET Core purposes by simply removing code we don't need in this configuration. We did a few easy initial steps but we can go much further.

This list is not comprehensive but parts like

• Culture Data
• Any PAL related code
• Unused icalls

Hello,
I run following code in ch 1.11.19(debug)，and it will crash by an assertion.

let b = [1.1, 2.2, 3.3];
b[4294967294] = 3;
Array.prototype.copyWithin.call(b, 0, 1);

Crash output:

ASSERTION 7690: (/.../ChakraCore-1.11.19/lib/Runtime/Library/JavascriptArray.cpp, line 9309) direction == -1 || (fromVal + count < MaxArrayLength && toVal + count < MaxArrayLength)
 Failure: (d