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

libraries/tools/kotlin-js-tests-junit/src/test/kotlin/tests/SeleniumTestSuite.kt

@@ -14,7 +14,7 @@ public class SeleniumTest(val id: String) {
         println("Testing $id")
     }
 
-    class object {
+    default object {
         Parameters public fun findSeleniumUris(): List<String> {
             return arrayList("a", "b")
         }

libraries/tools/kotlin-stdlib-gen/src/generators/GenerateJavaScriptStubs.kt

@@ -150,7 +150,7 @@ $imports
             if (fields != null) {
                 if (fields.isNotEmpty()) {
                     println("")
-                    println("    public class object {")
+                    println("    public default object {")
                     for (field in fields) {
                         if (field != null) {
                             val modifiers = field.getModifiers()