Move .java and .kotlin extension properties to kotlin.jvm

Delete the old ones in package kotlin.reflect.jvm because otherwise the code
using those functions will become red in a lot less meaningful way (overload
resolution ambiguity) than if they're deleted (unresolved import)

Based on the work originally done by @dnpetrov

 #KT-8380 Fixed

libraries/stdlib/src/kotlin/jvm/JvmClassMapping.kt

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2010-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kotlin.jvm
+
+import kotlin.jvm.internal.ClassBasedDeclarationContainer
+import kotlin.jvm.internal.Intrinsic
+import kotlin.jvm.internal.Reflection
+import kotlin.reflect.KClass
+
+/**
+ * Returns a Java [Class] instance corresponding to the given [KClass] instance.
+ */
+@Intrinsic("kotlin.KClass.java.property")
+public val <T> KClass<T>.java: Class<T>
+    get() = (this as ClassBasedDeclarationContainer).jClass as Class<T>
+
+/**
+ * Returns a [KClass] instance corresponding to the given Java [Class] instance.
+ */
+public val <T> Class<T>.kotlin: KClass<T>
+    get() = Reflection.createKotlinClass(this) as KClass<T>

libraries/stdlib/src/kotlin/util/JLangJVM.kt

@@ -27,13 +27,16 @@ public annotation(retention = AnnotationRetention.SOURCE) class throws(public va
 /**
  * Returns the runtime Java class of this object.
  */
-@Intrinsic("kotlin.javaClass.property") public val <T: Any> T.javaClass : Class<T>
+@Intrinsic("kotlin.javaClass.property")
+public val <T: Any> T.javaClass : Class<T>
     get() = (this as java.lang.Object).getClass() as Class<T>
 
 /**
  * Returns the Java class for the specified type.
  */
-@Intrinsic("kotlin.javaClass.function") public fun <reified T: Any> javaClass(): Class<T> = null as Class<T>
+@Intrinsic("kotlin.javaClass.function")
+@deprecated("Use the class reference and .java extension property instead: MyClass::class.java", ReplaceWith("T::class.java"))
+public fun <reified T: Any> javaClass(): Class<T> = T::class.java
 
 /**
  * Executes the given function [block] while holding the monitor of the given object [lock].