Minor, move diagnostic tests for class objects

compiler/testData/diagnostics/tests/classObjects/ClassObjectCannotAccessClassFields.kt

@@ -0,0 +1,9 @@
+// http://youtrack.jetbrains.net/issue/KT-20
+
+class A() {
+    val x = 1
+
+    class object {
+        val y = <!INACCESSIBLE_OUTER_CLASS_EXPRESSION!>x<!>
+    }
+}

compiler/testData/diagnostics/tests/classObjects/ClassObjectVisibility.kt

@@ -0,0 +1,22 @@
+package foo
+
+fun test() {
+  A.d
+  A.<!INVISIBLE_MEMBER!>f<!>
+  CCC.<!INVISIBLE_MEMBER!>classObjectVar<!>
+}
+
+class A() {
+  public class object {
+    val d = 3
+    private object f {
+
+    }
+  }
+}
+
+class CCC() {
+  private class object {
+    val classObjectVar = 3
+  }
+}

compiler/testData/diagnostics/tests/classObjects/ClassObjects.kt

@@ -0,0 +1,31 @@
+
+package Jet86
+
+class A {
+  class object {
+    val x = 1
+  }
+  <!MANY_CLASS_OBJECTS!>class object { // error
+    val x = 1
+  }<!>
+}
+
+class B() {
+  val x = 12
+}
+
+object b {
+  <!CLASS_OBJECT_NOT_ALLOWED!>class object {
+    val x = 1
+  }<!> // error
+}
+
+val a = A.x
+val c = B.<!UNRESOLVED_REFERENCE!>x<!>
+val d = b.<!UNRESOLVED_REFERENCE!>x<!>
+
+val s = <!NO_CLASS_OBJECT!>System<!>  // error
+fun test() {
+  System.out.println()
+  java.lang.System.out.println()
+}

compiler/testData/diagnostics/tests/classObjects/InnerClassClassObject.kt

@@ -0,0 +1,25 @@
+// http://youtrack.jetbrains.net/issue/KT-449
+
+class A {
+    inner class B {
+        <!CLASS_OBJECT_NOT_ALLOWED!>class object { }<!>
+    }
+}
+
+class B {
+    class object {
+        class B {
+            class object {
+                class C {
+                    class object { }
+                }
+            }
+        }
+    }
+}
+
+class C {
+    class D {
+        class object { }
+    }
+}