Disallow packed encoding of literals.

test/libsolidity/syntaxTests/tight_packing_literals.sol

@@ -5,4 +5,4 @@ contract C {
 }
 
 // ----
-// Warning: (92-93): The type of "int_const 1" was inferred as uint8. This is probably not desired. Use an explicit type to silence this warning.
+// TypeError: (92-93): Cannot perform packed encoding for a literal. Please convert it to an explicit type first.

test/libsolidity/syntaxTests/tight_packing_literals_050.sol

@@ -1,9 +0,0 @@
-pragma experimental "v0.5.0";
-contract C {
-    function k() pure public returns (bytes) {
-        return abi.encodePacked(1);
-    }
-}
-
-// ----
-// TypeError: (122-123): Cannot perform packed encoding for a literal. Please convert it to an explicit type first.