Fix KAnnotatedElement.findAnnotation when no annotation is found

#KT-15540 Fixed

compiler/testData/codegen/box/reflection/annotations/findAnnotation.kt

@@ -2,6 +2,7 @@
 // WITH_REFLECT
 
 import kotlin.reflect.findAnnotation
+import kotlin.test.assertNull
 
 annotation class Yes(val value: String)
 annotation class No(val value: String)
@@ -10,6 +11,11 @@ annotation class No(val value: String)
 @No("Fail")
 class Foo
 
+class Bar
+
 fun box(): String {
+    assertNull(Bar::class.findAnnotation<Yes>())
+    assertNull(Bar::class.findAnnotation<No>())
+
     return Foo::class.findAnnotation<Yes>()?.value ?: "Fail: no annotation"
 }

compiler/testData/codegen/light-analysis/reflection/annotations/findAnnotation.txt

@@ -1,3 +1,8 @@
+@kotlin.Metadata
+public final class Bar {
+    public method <init>(): void
+}
+
 @kotlin.Metadata
 public final class FindAnnotationKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String

core/reflection.jvm/src/kotlin/reflect/KAnnotatedElements.kt

@@ -23,4 +23,4 @@ package kotlin.reflect
 @Deprecated("Use 'findAnnotation' from kotlin.reflect.full package", ReplaceWith("this.findAnnotation<T>()", "kotlin.reflect.full.findAnnotation"), level = DeprecationLevel.WARNING)
 @Suppress("UNCHECKED_CAST")
 inline fun <reified T : Annotation> KAnnotatedElement.findAnnotation(): T? =
-        annotations.first { it is T } as T
+        annotations.firstOrNull { it is T } as T?

core/reflection.jvm/src/kotlin/reflect/full/KAnnotatedElements.kt

@@ -24,4 +24,4 @@ import kotlin.reflect.*
  */
 @Suppress("UNCHECKED_CAST")
 inline fun <reified T : Annotation> KAnnotatedElement.findAnnotation(): T? =
-        annotations.first { it is T } as T
+        annotations.firstOrNull { it is T } as T?