Service Worker: Correct WindowClient.idl

Source/modules/serviceworkers/WindowClient.idl

Index: Source/modules/serviceworkers/WindowClient.idl
diff --git a/Source/modules/serviceworkers/WindowClient.idl b/Source/modules/serviceworkers/WindowClient.idl
index 40a5ddcd783c940bdc2839a2ab0d393396fb3c70..3af859b12a83640eac243b5cd89dabe784ccf3f2 100644
--- a/Source/modules/serviceworkers/WindowClient.idl
+++ b/Source/modules/serviceworkers/WindowClient.idl
@@ -20,6 +20,5 @@ enum ContextFrameType {
 ] interface WindowClient : Client {
     readonly attribute VisibilityState visibilityState;
     readonly attribute boolean focused;
-    readonly attribute ContextFrameType frameType;

[zino, 2015/07/03 02:38:57]

Clarify: This is already defined in Client and we don't need to redefine.
            This change doesn't affect any behavior.

-    [CallWith=ScriptState] Promise<boolean> focus();
+    [CallWith=ScriptState] Promise<WindowClient> focus();

[nhiroki, 2015/07/03 03:18:08]

A promise resolution value type is just an annotation in WebIDL, so this change
does not affect actual implementation. OK, LGTM.

[falken, 2015/07/03 03:22:49]

Doesn't the C++ code need updating too? I assume we're resolving with a boolean
now.

And we don't have tests that test the return value of focus()? Can you add them?

 };