FE: forbid extension calls on inline functional parameters

Extension receivers are currently implicitly noinline, and changing that
would require modifying the syntax to allow marking them noinline or
crossinline.

^KT-5837 Open
^KT-25787 Fixed
^KT-47965 Fixed
^KT-50107 Fixed
^KT-52403 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/checkers/InlineChecker.kt

@@ -238,12 +238,12 @@ internal class InlineChecker(private val descriptor: FunctionDescriptor) : CallC
         if (descriptor !is SimpleFunctionDescriptor) {
             return false
         }
+        // TODO: receivers are currently not inline (KT-5837)
+        // if (InlineUtil.isInline(descriptor)) return true
 
         val containingDeclaration = descriptor.getContainingDeclaration()
-        val isInvoke = descriptor.getName() == OperatorNameConventions.INVOKE &&
+        return descriptor.getName() == OperatorNameConventions.INVOKE &&
                 containingDeclaration is ClassDescriptor && containingDeclaration.defaultType.isBuiltinFunctionalType
-
-        return isInvoke || InlineUtil.isInline(descriptor)
     }
 
     private fun checkVisibilityAndAccess(