dedicated safe integer truncation integration test (#435)

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

crates/integration/src/cases.rs

@@ -234,6 +234,15 @@ sol!(
 );
 case!("MCopy.sol", MCopy, memcpyCall, memcpy, payload: Bytes);
 
+sol!(
+    contract MLoad {
+        constructor() payable;
+
+        function loadAt(uint _offset) public payable returns (uint m);
+    }
+);
+case!("MLoad.sol", MLoad, loadAtCall, load_at, _offset: U256);
+
 sol!(
     contract Call {
         function value_transfer(address payable destination) public payable;