Have definite assignment assertions on property signatures mark them as typescript (#35270)

src/compiler/binder.ts

@@ -3643,7 +3643,7 @@ namespace ts {
         let transformFlags = subtreeFlags | TransformFlags.ContainsClassFields;
 
         // Decorators, TypeScript-specific modifiers, and type annotations are TypeScript syntax.
-        if (some(node.decorators) || hasModifier(node, ModifierFlags.TypeScriptModifier) || node.type || node.questionToken) {
+        if (some(node.decorators) || hasModifier(node, ModifierFlags.TypeScriptModifier) || node.type || node.questionToken || node.exclamationToken) {
             transformFlags |= TransformFlags.AssertTypeScript;
         }
 

tests/baselines/reference/definiteAssignmentWithErrorStillStripped.errors.txt

@@ -0,0 +1,9 @@
+tests/cases/compiler/definiteAssignmentWithErrorStillStripped.ts(2,6): error TS1255: A definite assignment assertion '!' is not permitted in this context.
+
+
+==== tests/cases/compiler/definiteAssignmentWithErrorStillStripped.ts (1 errors) ====
+    class C {
+        p!;
+         ~
+!!! error TS1255: A definite assignment assertion '!' is not permitted in this context.
+    }

tests/baselines/reference/definiteAssignmentWithErrorStillStripped.js

@@ -0,0 +1,9 @@
+//// [definiteAssignmentWithErrorStillStripped.ts]
+class C {
+    p!;
+}
+
+//// [definiteAssignmentWithErrorStillStripped.js]
+class C {
+    p;
+}

tests/baselines/reference/definiteAssignmentWithErrorStillStripped.symbols

@@ -0,0 +1,7 @@
+=== tests/cases/compiler/definiteAssignmentWithErrorStillStripped.ts ===
+class C {
+>C : Symbol(C, Decl(definiteAssignmentWithErrorStillStripped.ts, 0, 0))
+
+    p!;
+>p : Symbol(C.p, Decl(definiteAssignmentWithErrorStillStripped.ts, 0, 9))
+}

tests/baselines/reference/definiteAssignmentWithErrorStillStripped.types

@@ -0,0 +1,7 @@
+=== tests/cases/compiler/definiteAssignmentWithErrorStillStripped.ts ===
+class C {
+>C : C
+
+    p!;
+>p : any
+}

tests/cases/compiler/definiteAssignmentWithErrorStillStripped.ts

@@ -0,0 +1,5 @@
+// @target: esnext
+// @useDefineForClassFields: true
+class C {
+    p!;
+}