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

Replace some comments and library usages as well

generators/src/org/jetbrains/kotlin/generators/builtins/common.kt

@@ -30,7 +30,7 @@ enum class PrimitiveType {
     BOOLEAN
 
     val capitalized: String get() = name().toLowerCase().capitalize()
-    class object {
+    companion object {
         val exceptBoolean: Iterable<PrimitiveType> by Delegates.lazy { PrimitiveType.values().filterNot { it == BOOLEAN } }
     }
 }

generators/src/org/jetbrains/kotlin/generators/builtins/primitives.kt

@@ -61,7 +61,7 @@ class GeneratePrimitives(out: PrintWriter) : BuiltInsSourceGenerator(out) {
             }
             out.println("Comparable<$className> {")
 
-            out.print("    class object Companion")
+            out.print("    companion object")
             if (kind == PrimitiveType.FLOAT || kind == PrimitiveType.DOUBLE) {
                 out.print(" : FloatingPointConstants<$className>")
             }

generators/src/org/jetbrains/kotlin/generators/builtins/ranges.kt

@@ -82,7 +82,7 @@ public class $range(override val start: $t, override val end: $t) : Range<$t>, P
 
     override fun hashCode(): Int $hashCode
 
-    class object Companion {
+    companion object {
         /** An empty range of values of type $t. */
         public val EMPTY: $range = $range($emptyBounds)
     }