... arguments parity from Flex and Royale

The parameter ... arguments (documentation here: https://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/arguments.html) allows to create a function with an undefined number of arguments that can be iterated as an array inside the function.

In Flex world, this parameter writes this way: ... arguments, however in Royale world the only way to compile is this way: ... Arguments (notice the "A" instead of "a").

Royale ex:

public function call(... Arguments):void //this line will not work with ... arguments
{
}

call("1", "2", "3");

Start by reproducing the two Royale examples and comparing them with the linked ActionScript arguments documentation. Locate the compiler entry point that handles the variadic `... arguments` parameter and verify that the lowercase spelling compiles and behaves like the existing uppercase form; add or run a regression test if the relevant test location is found.

Written by the indexing model from the issue text.