Add regression tests for obsolete issues

#KT-1291 Obsolete
 #KT-2895 Obsolete
 #KT-3060 Obsolete
 #KT-3298 Obsolete
 #KT-3613 Obsolete
 #KT-3862 Obsolete

compiler/testData/codegen/box/extensionFunctions/kt3298.kt

@@ -0,0 +1,13 @@
+var result = ""
+fun result(r: String) { result = r }
+
+object Foo {
+    private fun String.plus() = "(" + this + ")"
+
+    fun foo() = { result(+"Stuff") }()
+}
+
+fun box(): String {
+    Foo.foo()
+    return if (result == "(Stuff)") "OK" else "Fail $result"
+}