Use stubs in reduced js-ir runtime instead of new throwable extensions

To avoid bringing a lot of API required for their full implementation
to reduced runtime.

libraries/stdlib/js-ir/smallRuntime/smallRuntimeMissingDeclarations.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -19,3 +19,17 @@ public inline fun <T, R> Array<out T>.fold(initial: R, operation: (acc: R, T) ->
     for (element in this) accumulator = operation(accumulator, element)
     return accumulator
 }
+
+
+public actual fun Throwable.stackTraceToString(): String = toString()
+
+public actual fun Throwable.printStackTrace() {
+    TODO("Not implemented in reduced runtime")
+}
+
+public actual fun Throwable.addSuppressed(exception: Throwable) {
+    TODO("Not implemented in reduced runtime")
+}
+
+public actual val Throwable.suppressedExceptions: List<Throwable>
+    get() = TODO("Not implemented in reduced runtime")