Get rid of 'class object' usages in code and builtins

Replace some comments and library usages as well

core/builtins/native/kotlin/Enum.kt

@@ -22,7 +22,7 @@ package kotlin
  * information on enum classes.
  */
 public abstract class Enum<E : Enum<E>>(name: String, ordinal: Int): Comparable<E> {
-    class object Companion {}
+    companion object {}
 
     /**
      * Returns the name of this enum constant, exactly as declared in its enum declaration.

core/builtins/native/kotlin/Primitives.kt

@@ -23,7 +23,7 @@ package kotlin
  * On the JVM, non-nullable values of this type are represented as values of the primitive type `byte`.
  */
 public class Byte private () : Number, Comparable<Byte> {
-    class object Companion {}
+    companion object {}
 
 /**
  * Compares this value with the specified value for order.
@@ -181,7 +181,7 @@ public class Byte private () : Number, Comparable<Byte> {
  * On the JVM, non-nullable values of this type are represented as values of the primitive type `char`.
  */
 public class Char private () : Comparable<Char> {
-    class object Companion {}
+    companion object {}
 
 /**
  * Compares the character code of this character with the specified value for order.
@@ -326,7 +326,7 @@ public class Char private () : Comparable<Char> {
  * On the JVM, non-nullable values of this type are represented as values of the primitive type `short`.
  */
 public class Short private () : Number, Comparable<Short> {
-    class object Companion {}
+    companion object {}
 
 /**
  * Compares this value with the specified value for order.
@@ -484,7 +484,7 @@ public class Short private () : Number, Comparable<Short> {
  * On the JVM, non-nullable values of this type are represented as values of the primitive type `int`.
  */
 public class Int private () : Number, Comparable<Int> {
-    class object Companion {}
+    companion object {}
 
 /**
  * Compares this value with the specified value for order.
@@ -657,7 +657,7 @@ public class Int private () : Number, Comparable<Int> {
  * On the JVM, non-nullable values of this type are represented as values of the primitive type `long`.
  */
 public class Long private () : Number, Comparable<Long> {
-    class object Companion {}
+    companion object {}
 
 /**
  * Compares this value with the specified value for order.
@@ -830,7 +830,7 @@ public class Long private () : Number, Comparable<Long> {
  * On the JVM, non-nullable values of this type are represented as values of the primitive type `float`.
  */
 public class Float private () : Number, Comparable<Float> {
-    class object Companion : FloatingPointConstants<Float> {}
+    companion object : FloatingPointConstants<Float> {}
 
 /**
  * Compares this value with the specified value for order.
@@ -988,7 +988,7 @@ public class Float private () : Number, Comparable<Float> {
  * On the JVM, non-nullable values of this type are represented as values of the primitive type `double`.
  */
 public class Double private () : Number, Comparable<Double> {
-    class object Companion : FloatingPointConstants<Double> {}
+    companion object : FloatingPointConstants<Double> {}
 
 /**
  * Compares this value with the specified value for order.

core/builtins/native/kotlin/String.kt

@@ -21,7 +21,7 @@ package kotlin
  * implemented as instances of this class.
  */
 public class String : Comparable<String>, CharSequence {
-    class object Companion {}
+    companion object {}
     
     /**
      * Returns a string obtained by concatenating this string with the string representation of the given [other] object.

core/builtins/src/kotlin/Ranges.kt

@@ -38,7 +38,7 @@ public class ByteRange(override val start: Byte, override val end: Byte) : Range
     override fun hashCode(): Int =
         if (isEmpty()) -1 else (31 * start.toInt() + end)
 
-    class object Companion {
+    companion object {
         /** An empty range of values of type Byte. */
         public val EMPTY: ByteRange = ByteRange(1, 0)
     }
@@ -64,7 +64,7 @@ public class CharRange(override val start: Char, override val end: Char) : Range
     override fun hashCode(): Int =
         if (isEmpty()) -1 else (31 * start.toInt() + end)
 
-    class object Companion {
+    companion object {
         /** An empty range of values of type Char. */
         public val EMPTY: CharRange = CharRange(1.toChar(), 0.toChar())
     }
@@ -90,7 +90,7 @@ public class ShortRange(override val start: Short, override val end: Short) : Ra
     override fun hashCode(): Int =
         if (isEmpty()) -1 else (31 * start.toInt() + end)
 
-    class object Companion {
+    companion object {
         /** An empty range of values of type Short. */
         public val EMPTY: ShortRange = ShortRange(1, 0)
     }
@@ -116,7 +116,7 @@ public class IntRange(override val start: Int, override val end: Int) : Range<In
     override fun hashCode(): Int =
         if (isEmpty()) -1 else (31 * start + end)
 
-    class object Companion {
+    companion object {
         /** An empty range of values of type Int. */
         public val EMPTY: IntRange = IntRange(1, 0)
     }
@@ -142,7 +142,7 @@ public class LongRange(override val start: Long, override val end: Long) : Range
     override fun hashCode(): Int =
         if (isEmpty()) -1 else (31 * (start xor (start ushr 32)) + (end xor (end ushr 32))).toInt()
 
-    class object Companion {
+    companion object {
         /** An empty range of values of type Long. */
         public val EMPTY: LongRange = LongRange(1, 0)
     }
@@ -168,7 +168,7 @@ public class FloatRange(override val start: Float, override val end: Float) : Ra
     override fun hashCode(): Int =
         if (isEmpty()) -1 else (31 * java.lang.Float.floatToIntBits(start) + java.lang.Float.floatToIntBits(end))
 
-    class object Companion {
+    companion object {
         /** An empty range of values of type Float. */
         public val EMPTY: FloatRange = FloatRange(1.0f, 0.0f)
     }
@@ -199,7 +199,7 @@ public class DoubleRange(override val start: Double, override val end: Double) :
         return (31 * result + (temp xor (temp ushr 32))).toInt()
     }
 
-    class object Companion {
+    companion object {
         /** An empty range of values of type Double. */
         public val EMPTY: DoubleRange = DoubleRange(1.0, 0.0)
     }