Adding createFlowUnionType in place of createUnionTypeAnnotati… (#11448)

* 🔄 createUnionTypeAnnotation => createFlowUnionType

* ➕ add createFlowUnionType if it exists (in new versions only ⚠️)

* 🔄 use createFlowUnionType for createUnionTypeAnnotation

packages/babel-traverse/src/path/inference/inferer-reference.js

@@ -99,6 +99,10 @@ function getTypeAnnotationBindingConstantViolations(binding, path, name) {
     return t.createTSUnionType(types);
   }
 
+  if (t.createFlowUnionType) {
+    return t.createFlowUnionType(types);
+  }
+
   return t.createUnionTypeAnnotation(types);
 }
 
@@ -214,6 +218,13 @@ function getConditionalAnnotation(binding, path, name) {
       };
     }
 
+    if (t.createFlowUnionType) {
+      return {
+        typeAnnotation: t.createFlowUnionType(types),
+        ifStatement,
+      };
+    }
+
     return {
       typeAnnotation: t.createUnionTypeAnnotation(types),
       ifStatement,