Transform variable-as-function calls for extension functions

In the following code example
  fun test(f: Any.() -> Unit) = 42.f()
front-end resolves variable-as-function call for 'f' as 'invoke'
with signature 'Function1<Any, Unit>#Any.() -> Unit'.
However, Function1<Any, Unit> has a single 'invoke' method
with signature 'Function1<Any, Unit>#(Any) -> Unit'.
This didn't cause any problems with loosely typed JVM and JS back-ends.
However, in IR with symbols this means a reference to non-existing
declaration.

compiler/tests/org/jetbrains/kotlin/ir/IrTextTestCaseGenerated.java

@@ -635,6 +635,12 @@ public class IrTextTestCaseGenerated extends AbstractIrTextTestCase {
             doTest(fileName);
         }
 
+        @TestMetadata("extFunSafeInvoke.kt")
+        public void testExtFunSafeInvoke() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irText/expressions/extFunSafeInvoke.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("extensionPropertyGetterCall.kt")
         public void testExtensionPropertyGetterCall() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irText/expressions/extensionPropertyGetterCall.kt");