Add internal WasExperimental for stdlib

Usages of declarations annotated with WasExperimental are allowed even
if the API version requirement is not satisfied, provided that the
opt-in to all mentioned markers is given. This is needed for smooth
graduation of API in kotlin-stdlib

compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.kt

@@ -0,0 +1,45 @@
+// !API_VERSION: 1.2
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// !DIAGNOSTICS: -INVISIBLE_MEMBER -INVISIBLE_REFERENCE -NEWER_VERSION_IN_SINCE_KOTLIN -UNUSED_PARAMETER
+
+@SinceKotlin("1.3")
+fun newPublishedFun() {}
+
+
+@Experimental
+annotation class Marker
+
+@SinceKotlin("1.3")
+@WasExperimental(Marker::class)
+fun newFunExperimentalInThePast() {}
+
+@SinceKotlin("1.3")
+@WasExperimental(Marker::class)
+val newValExperimentalInThePast = ""
+
+@SinceKotlin("1.3")
+@WasExperimental(Marker::class)
+class NewClassExperimentalInThePast
+
+fun use1(c: <!UNRESOLVED_REFERENCE!>NewClassExperimentalInThePast<!>) {
+    <!UNRESOLVED_REFERENCE!>newPublishedFun<!>()
+    <!UNRESOLVED_REFERENCE!>newFunExperimentalInThePast<!>()
+    <!UNRESOLVED_REFERENCE!>newValExperimentalInThePast<!>
+    <!UNRESOLVED_REFERENCE!>NewClassExperimentalInThePast<!>()
+}
+
+@UseExperimental(Marker::class)
+fun use2(c: NewClassExperimentalInThePast) {
+    <!UNRESOLVED_REFERENCE!>newPublishedFun<!>()
+    newFunExperimentalInThePast()
+    newValExperimentalInThePast
+    NewClassExperimentalInThePast()
+}
+
+@Marker
+fun use3(c: NewClassExperimentalInThePast) {
+    <!UNRESOLVED_REFERENCE!>newPublishedFun<!>()
+    newFunExperimentalInThePast()
+    newValExperimentalInThePast
+    NewClassExperimentalInThePast()
+}

compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.txt

@@ -0,0 +1,14 @@
+package
+
+@kotlin.SinceKotlin(version = "1.3") @kotlin.WasExperimental(markerClass = {Marker::class}) public fun newFunExperimentalInThePast(): kotlin.Unit
+@kotlin.SinceKotlin(version = "1.3") public fun newPublishedFun(): kotlin.Unit
+public fun use1(): kotlin.Unit
+@kotlin.UseExperimental(markerClass = {Marker::class}) public fun use2(): kotlin.Unit
+@Marker public fun use3(): kotlin.Unit
+
+@kotlin.Experimental public final annotation class Marker : kotlin.Annotation {
+    public constructor Marker()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}