Minor: replace some missed mentions of 'class object' with 'default object'

compiler/frontend/src/org/jetbrains/kotlin/descriptors/impl/MutableClassDescriptor.java

@@ -98,7 +98,7 @@ public class MutableClassDescriptor extends ClassDescriptorBase implements Class
         return defaultObjectDescriptor;
     }
 
-    public void setClassObjectDescriptor(@NotNull MutableClassDescriptor classObjectDescriptor) {
+    public void setDefaultObjectDescriptor(@NotNull MutableClassDescriptor classObjectDescriptor) {
         assert this.defaultObjectDescriptor == null : "classObjectDescriptor already assigned in " + this;
         this.defaultObjectDescriptor = classObjectDescriptor;
     }

js/js.translator/testData/inlineStdlib/cases/callNameClash.kt

@@ -7,7 +7,7 @@ fun f(x: Int): Int = x * 2
 fun Int.f(): Int = this * 3
 
 class A(var value: Int) {
-    class object {
+    default object {
         fun f(): Int = 5
     }