Fix ICE caused by an array of mappings

test/libsolidity/syntaxTests/array/pop/storage_with_mapping_pop.sol

@@ -0,0 +1,7 @@
+contract C {
+    mapping(uint=>uint)[] array;
+    mapping(uint=>uint) map;
+    function f() public {
+        array.pop();
+    }
+}

test/libsolidity/syntaxTests/array/push/storage_with_mapping_push.sol

@@ -0,0 +1,10 @@
+contract C {
+    mapping(uint=>uint)[] array;
+    mapping(uint=>uint) map;
+    function f() public {
+        array.push();
+        array.push(map);
+    }
+}
+// ----
+// TypeError 8871: (131-141): Storage arrays with nested mappings do not support .push(<arg>).