Avoid extra arity and type check on distinguishing argument

Source/bindings/tests/idls/TestObject.idl

Index: Source/bindings/tests/idls/TestObject.idl
diff --git a/Source/bindings/tests/idls/TestObject.idl b/Source/bindings/tests/idls/TestObject.idl
index 3ec4e3c54b67bf70b8b55c39fa265ec244c12900..56405bfe4e7cdf6e7bedd592262cb04342f9028e 100644
--- a/Source/bindings/tests/idls/TestObject.idl
+++ b/Source/bindings/tests/idls/TestObject.idl
@@ -410,6 +410,11 @@ interface TestObject {
     void overloadedMethodK(TestInterfaceEmpty testInterfaceEmptyArg);
     void overloadedMethodL(DOMString stringArg);
     void overloadedMethodL(double doubleArg);
+    [TypeChecking=Interface] void overloadedMethodM(TestInterface testInterfaceArg1, TestInterface testInterfaceArg2);
+    [TypeChecking=Interface] void overloadedMethodM(TestInterface testInterfaceArg, TestInterfaceEmpty testInterfaceEmptyArg);
+    [TypeChecking=Interface] void overloadedMethodN(double a, TestInterface b);

[Nils Barth (inactive), 2014/05/16 02:15:46]

You don't need the double here do you?
...and this is subtle enough that some comment on what's being tested would be
good:
// 2 distinguishing argument indices in second method, due to optionality

[Jens Widell, 2014/05/16 05:59:17]

Don't think I do, no. Unclear why I thought I did.
Yeah. By the time I added this, I had sort of already abandoned this CL in my
mind anyway, so wasn't being too thorough here.

Do you think it meaningful to add these methods on their own?

[Nils Barth (inactive), 2014/05/16 06:05:31]

I don't think that's necessary, but thanks for asking!
Generally we only add test cases when there's an actual use case that fails
otherwise, not just for internal correctness tests.

(We try to keep CG and test cases close to actual usage: that's why I've been
avoiding adding correct CG code that's unused: dead code rots quickly around
here.)

+    [TypeChecking=Interface] void overloadedMethodN(double a, TestInterfaceEmpty b, optional TestInterface c);
+    [TypeChecking=Interface] void overloadedMethodN(double a, TestInterfaceEmpty b, TestInterfaceEmpty c);
 
 
     [PerWorldBindings] void overloadedPerWorldBindingsMethod();