Delete assertion on receiver presence in 'invoke'

#KT-6541 Fixed
 #KT-7383 Fixed

compiler/testData/diagnostics/tests/functionLiterals/kt6541_extensionForExtensionFunction.kt

@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo
+fun (Foo.() -> Unit).invoke(b : Foo.() -> Unit)  {}
+
+object Z {
+    fun add(b : Foo.() -> Unit) : Z = Z
+}
+
+val t2 = Z add <!TYPE_MISMATCH!>{ } <!TOO_MANY_ARGUMENTS!>{ }<!><!>