quadratic memory charge

src/gas.rs

@@ -48,6 +48,10 @@ fn add_grow_counter(module: elements::Module, rules: &rules::Set, gas_func: u32)
 					GetLocal(0),
 					I32Const(rules.grow_cost() as i32),
 					I32Mul,
+					CurrentMemory(0),
+					I32Const(1),
+					I32Add,
+					I32Mul,
 					// todo: there should be strong guarantee that it does not return anything on stack?
 					Call(gas_func),
 					GrowMemory(0),
@@ -244,6 +248,10 @@ mod tests {
 				GetLocal(0),
 				I32Const(10000),
 				I32Mul,
+				CurrentMemory(0),
+				I32Const(1),
+				I32Add,
+				I32Mul,
 				Call(0),
 				GrowMemory(0),
 				GetLocal(0),