Implement assumptions defined in the babel/rfcs#5 RFC

- `mutableTemplateObject` and `ignoreToPrimitiveHint` (#12408)
- `setClassMethods` (#12407)
- `setComputedProperties` (#12490)
- `ignoreFunctionLength` (#12491)
- `noDocumentAll` (#12481)
- `iterableIsArray` and `arrayLikeIsIterable` (#12489)
- `pureGetters` (#12504)
- `skipForOfIteratorClosing` (#12496)
- `objectRestNoSymbols`, `setSpreadProperties` and `pureGetters` (#12505)
- `noNewArrows` (#12613, #12793)
- `setPublicClassFields` and `privateFieldsAsProperties` (#12497)
- `constantReexports` and `enumerableModuleMeta` (#12618)
- `constantSuper`, `superIsCallableConstructor` and `noClassCalls` (#12726)

Co-authored-by: Justin Ridgewell <justin@ridgewell.name>
Co-authored-by: Huáng Jùnliàng <JLHwung@users.noreply.github.com>

packages/babel-plugin-transform-modules-umd/src/index.js

@@ -44,13 +44,17 @@ export default declare((api, options) => {
   const {
     globals,
     exactGlobals,
-    loose,
     allowTopLevelThis,
     strict,
     strictMode,
     noInterop,
   } = options;
 
+  const constantReexports =
+    api.assumption("constantReexports") ?? options.loose;
+  const enumerableModuleMeta =
+    api.assumption("enumerableModuleMeta") ?? options.loose;
+
   /**
    * Build the assignment statements that initialize the UMD global.
    */
@@ -147,7 +151,8 @@ export default declare((api, options) => {
           const { meta, headers } = rewriteModuleStatementsAndPrepareHeader(
             path,
             {
-              loose,
+              constantReexports,
+              enumerableModuleMeta,
               strict,
               strictMode,
               allowTopLevelThis,
@@ -201,7 +206,11 @@ export default declare((api, options) => {
             }
 
             headers.push(
-              ...buildNamespaceInitStatements(meta, metadata, loose),
+              ...buildNamespaceInitStatements(
+                meta,
+                metadata,
+                constantReexports,
+              ),
             );
           }