KJS: use cached KClass instead create new each time when getting it from JsClass

js/js.libraries/src/reflect/JsClass.kt

@@ -16,6 +16,7 @@
 
 package kotlin.js
 
+import getKClass
 import kotlin.reflect.KClass
 import kotlin.reflect.js.internal.KClassImpl
 
@@ -36,4 +37,4 @@ val <T : Any> KClass<T>.js: JsClass<T>
     get() = (this as KClassImpl<T>).jClass
 
 val <T : Any> JsClass<T>.kotlin: KClass<T>
-    get() = KClassImpl<T>(this)
+    get() = getKClass(this)

js/js.libraries/src/reflect/reflection.kt

@@ -20,9 +20,9 @@ import kotlin.reflect.KClass
 import kotlin.reflect.js.internal.KClassImpl
 
 @JsName("getKClass")
-private fun <T : Any> getKClass(jClass: JsClass<T>): KClass<T> = getOrCreateKClass(jClass)
+internal fun <T : Any> getKClass(jClass: JsClass<T>): KClass<T> = getOrCreateKClass(jClass)
 @JsName("getKClassFromExpression")
-private fun <T : Any> getKClassFromExpression(e: T): KClass<T> = getOrCreateKClass(e.jsClass)
+internal fun <T : Any> getKClassFromExpression(e: T): KClass<T> = getOrCreateKClass(e.jsClass)
 
 private fun <T : Any> getOrCreateKClass(jClass: JsClass<T>): KClass<T> {
     val metadata = jClass.asDynamic().`$metadata$`

js/js.translator/testData/_commonFiles/asserts.kt

@@ -18,6 +18,13 @@ fun <T> assertNotEquals(illegal: T, actual: T, message: String? = null) {
     }
 }
 
+fun <T> assertSame(expected: T, actual: T, message: String? = null) {
+    if (expected !== actual) {
+        val msg = if (message == null) "" else (" message = '" + message + "',")
+        fail("Expected same instances, got expected = '$expected', actual = '$actual'")
+    }
+}
+
 fun <T> assertArrayEquals(expected: Array<out T>, actual: Array<out T>, message: String? = null) {
     if (!arraysEqual(expected, actual)) {
         val msg = if (message == null) "" else (" message = '" + message + "',")

js/js.translator/testData/box/reflection/kClassToAndFromJsClass.kt

@@ -6,10 +6,10 @@ fun check(k: KClass<*>, j: JsClass<*>) {
     assertNotEquals(null, k)
     assertNotEquals(null, j)
 
-    assertEquals(k.js, j)
+    assertSame(k.js, j)
-    assertEquals(k, j.kotlin)
+    assertSame(k, j.kotlin)
-    assertEquals(j, j.kotlin.js)
+    assertSame(j, j.kotlin.js)
-    assertEquals(k, k.js.kotlin)
+    assertSame(k, k.js.kotlin)
 }
 
 fun jsClassbyName(name: String) = js("JS_TESTS").foo[name]