Remove parser support for decorators optional parentheses (#8037)

* Remove parser support for decorators optional parentheses

* Update fixtures

packages/babel-types/README.md

@@ -600,13 +600,12 @@ Aliases: `Flow`, `FlowPredicate`
 
 ### decorator
 ```javascript
-t.decorator(callee, arguments)
+t.decorator(expression)
 ```
 
 See also `t.isDecorator(node, opts)` and `t.assertDecorator(node, opts)`.
 
- - `callee`: `Expression` (required)
- - `arguments`: `Array<Expression | SpreadElement>` (default: `null`)
+ - `expression`: `Expression` (required)
 
 ---
 

packages/babel-types/src/definitions/experimental.js

@@ -136,18 +136,11 @@ defineType("Import", {
 });
 
 defineType("Decorator", {
-  visitor: ["callee", "arguments"],
+  visitor: ["expression"],
   fields: {
-    callee: {
+    expression: {
       validate: assertNodeType("Expression"),
     },
-    arguments: {
-      optional: true,
-      validate: chain(
-        assertValueType("array"),
-        assertEach(assertNodeType("Expression", "SpreadElement")),
-      ),
-    },
   },
 });