Replace 'class object' with 'default object' in renderers and test data

Includes changes to decompiled text
Old syntax is used in builtins and project code for now

js/js.translator/testData/reservedWords/cases/toplevelClassPackage.kt

@@ -2,7 +2,7 @@ package foo
 
 // NOTE THIS FILE IS AUTO-GENERATED by the generateTestDataForReservedWords.kt. DO NOT EDIT!
 
-class `package` { class object {} }
+class `package` { default object {} }
 
 fun box(): String {
     testNotRenamed("package", { `package` })