Support per-overload [RuntimeEnabled] extended attribute

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 920966c09f853f6764599f4a6bb14b08c16672bd..9b4bd7dd98b52d5cf26fbed6dae14b64ded5396e 100644
--- a/Source/bindings/tests/idls/TestObject.idl
+++ b/Source/bindings/tests/idls/TestObject.idl
@@ -481,6 +481,10 @@ interface TestObject {
     [NotEnumerable, ReadOnly] void notEnumerableReadOnlyVoidMethod();
     [RuntimeEnabled=FeatureName] void runtimeEnabledVoidMethod();
     [PerWorldBindings, RuntimeEnabled=FeatureName] void perWorldBindingsRuntimeEnabledVoidMethod();
+    [RuntimeEnabled=FeatureName] void runtimeEnabledOverloadedVoidMethod(DOMString stringArg);
+    [RuntimeEnabled=FeatureName] void runtimeEnabledOverloadedVoidMethod(long longArg);
+    [RuntimeEnabled=FeatureName] void partiallyRuntimeEnabledOverloadedVoidMethod(DOMString stringArg);
+    void partiallyRuntimeEnabledOverloadedVoidMethod(long longArg);

[Nils Barth (inactive), 2014/06/12 11:45:06]

Do you want a test case with multiple feature names, possibly overlapping?
E.g.,
[RE=A]
[RE=B]
or:
[RE=A]
[RE=A&B]
Not necessary if we're not supporting this, but if you're
explicitly supporting this case, a test makes that clearer.

[Jens Widell, 2014/06/12 12:04:38]

Adding another partiallyRuntimeEnabledOverloadedVoidMethod() overload with a
different [RuntimeEnabled] is cheap enough to add, and might be somewhat
meaningful, but in practice doesn't exercise any additional code in the current
implementation.

Changing the [RuntimeEnabled] on one of the runtimeEnabledOverloadedVoidMethod()
overloads is not allowed; it triggers the "Function.length depends on runtime
flags" check. Makes some sense, since if both runtime flags are off, there
should be no method object and thus it's length is arguably undefined.

[Nils Barth (inactive), 2014/06/12 12:20:27]

Thanks for explanation; current tests are fine then!

     [TreatReturnedNullStringAs=Null] DOMString treatReturnedNullStringAsNullStringMethod();
     [TreatReturnedNullStringAs=Undefined] DOMString treatReturnedNullStringAsUndefinedStringMethod();
     [TypeChecking=Interface] void typeCheckingInterfaceVoidMethodTestInterfaceEmptyArg(TestInterfaceEmpty testInterfaceEmptyArg);