Implement basic completion for fields

crates/ra_syntax/src/ast/generated.rs

@@ -2030,6 +2030,10 @@ impl<'a> MethodCallExpr<'a> {
     pub fn expr(self) -> Option<Expr<'a>> {
         super::child_opt(self)
     }
+
+    pub fn name_ref(self) -> Option<NameRef<'a>> {
+        super::child_opt(self)
+    }
 }
 
 // Module

crates/ra_syntax/src/grammar.ron

@@ -403,7 +403,7 @@ Grammar(
         ),
         "MethodCallExpr": (
             traits: ["ArgListOwner"],
-            options: [ "Expr" ],
+            options: [ "Expr", "NameRef" ],
         ),
         "IndexExpr": (),
         "FieldExpr": (options: ["Expr", "NameRef"]),