Change error message and add tests

test/libsolidity/syntaxTests/types/encoding_fractional.sol

@@ -0,0 +1,7 @@
+contract C {
+   function f1() public pure returns (bytes memory) {
+       return abi.encode(0.1, 1);
+   }
+}
+// ----
+// TypeError: (92-95): Fractional numbers cannot yet be encoded.

test/libsolidity/syntaxTests/types/encoding_fractional_abiencoderv2.sol

@@ -0,0 +1,9 @@
+pragma experimental ABIEncoderV2;
+contract C {
+   function f1() public pure returns (bytes memory) {
+       return abi.encode(0.1, 1);
+   }
+}
+// ----
+// Warning: (0-33): Experimental features are turned on. Do not use experimental features on live deployments.
+// TypeError: (126-129): Fractional numbers cannot yet be encoded.

test/libsolidity/syntaxTests/types/encoding_packed_fractional.sol

@@ -0,0 +1,8 @@
+contract C {
+   function f1() public pure returns (bytes memory) {
+       return abi.encodePacked(0.1, 1);
+   }
+}
+// ----
+// TypeError: (98-101): Fractional numbers cannot yet be encoded.
+// TypeError: (103-104): Cannot perform packed encoding for a literal. Please convert it to an explicit type first.

test/libsolidity/syntaxTests/types/encoding_packed_fractional_abiencoderv2.sol

@@ -0,0 +1,10 @@
+pragma experimental ABIEncoderV2;
+contract C {
+   function f1() public pure returns (bytes memory) {
+       return abi.encodePacked(0.1, 1);
+   }
+}
+// ----
+// Warning: (0-33): Experimental features are turned on. Do not use experimental features on live deployments.
+// TypeError: (132-135): Fractional numbers cannot yet be encoded.
+// TypeError: (137-138): Cannot perform packed encoding for a literal. Please convert it to an explicit type first.