Support decorators on abstract classes

common/corpus/declarations.txt

@@ -744,6 +744,10 @@ abstract class Animal {
     }
 }
 
+@bar
+abstract class Foo {
+}
+
 ---
 
 (program
@@ -782,7 +786,11 @@ abstract class Animal {
             function: (member_expression
               object: (identifier)
               property: (property_identifier))
-            arguments: (arguments (string)))))))))
+            arguments: (arguments (string))))))))
+  (abstract_class_declaration
+    decorator: (decorator (identifier))
+    name: (type_identifier)
+    body: (class_body)))
 
 ==================================
 Index type queries

common/define-grammar.js

@@ -354,6 +354,7 @@ module.exports = function defineGrammar(dialect) {
       ),
 
       abstract_class_declaration: $ => seq(
+        repeat(field('decorator', $.decorator)),
         'abstract',
         'class',
         field('name', $._type_identifier),

typescript/src/grammar.json

@@ -6985,6 +6985,17 @@
     "abstract_class_declaration": {
       "type": "SEQ",
       "members": [
+        {
+          "type": "REPEAT",
+          "content": {
+            "type": "FIELD",
+            "name": "decorator",
+            "content": {
+              "type": "SYMBOL",
+              "name": "decorator"
+            }
+          }
+        },
         {
           "type": "STRING",
           "value": "abstract"

typescript/src/node-types.json

@@ -325,6 +325,16 @@
           }
         ]
       },
+      "decorator": {
+        "multiple": true,
+        "required": false,
+        "types": [
+          {
+            "type": "decorator",
+            "named": true
+          }
+        ]
+      },
       "name": {
         "multiple": false,
         "required": true,