Delete assertion on receiver presence in 'invoke'

#KT-6541 Fixed
 #KT-7383 Fixed

compiler/testData/diagnostics/tests/resolve/invoke/invokeNonExtensionLambdaInContext.kt

@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    fun f() {}
+}
+
+fun C.g(f: (String) -> Unit = { s -> f() }) {}