Improve handling of dictionary conversions.

LayoutTests/fast/events/constructors/media-stream-event-constructor.html

Index: LayoutTests/fast/events/constructors/media-stream-event-constructor.html
diff --git a/LayoutTests/fast/events/constructors/media-stream-event-constructor.html b/LayoutTests/fast/events/constructors/media-stream-event-constructor.html
index fd50139110d4021810b58d90198ec65e731b73c0..a7038a59a2273cabc059c277869f8868f5551e02 100644
--- a/LayoutTests/fast/events/constructors/media-stream-event-constructor.html
+++ b/LayoutTests/fast/events/constructors/media-stream-event-constructor.html
@@ -29,20 +29,21 @@ shouldBe("new MediaStreamEvent('eventType', { cancelable: true }).cancelable", "
 shouldBe("new MediaStreamEvent('eventType', { stream: mediaStream }).stream", "mediaStream");
 
 // Invalid objects.
-shouldBe("new MediaStreamEvent('eventType', { stream: testObject }).stream", "null");
-shouldBe("new MediaStreamEvent('eventType', { stream: document }).stream", "null");
+shouldThrow("new MediaStreamEvent('eventType', { stream: testObject }).stream");
+shouldThrow("new MediaStreamEvent('eventType', { stream: document }).stream");
 shouldBe("new MediaStreamEvent('eventType', { stream: undefined }).stream", "null");
 shouldBe("new MediaStreamEvent('eventType', { stream: null }).stream", "null");
-shouldBe("new MediaStreamEvent('eventType', { stream: false }).stream", "null");
-shouldBe("new MediaStreamEvent('eventType', { stream: true }).stream", "null");
-shouldBe("new MediaStreamEvent('eventType', { stream: '' }).stream", "null");
-shouldBe("new MediaStreamEvent('eventType', { stream: 'chocolate' }).stream", "null");
-shouldBe("new MediaStreamEvent('eventType', { stream: 12345 }).stream", "null");
-shouldBe("new MediaStreamEvent('eventType', { stream: 18446744073709551615 }).stream", "null");
-shouldBe("new MediaStreamEvent('eventType', { stream: NaN }).stream", "null");
+shouldThrow("new MediaStreamEvent('eventType', { stream: false }).stream");
+shouldThrow("new MediaStreamEvent('eventType', { stream: true }).stream");
+shouldThrow("new MediaStreamEvent('eventType', { stream: '' }).stream");
+shouldThrow("new MediaStreamEvent('eventType', { stream: 'chocolate' }).stream");
+shouldThrow("new MediaStreamEvent('eventType', { stream: 12345 }).stream");
+shouldThrow("new MediaStreamEvent('eventType', { stream: 18446744073709551615 }).stream");
+shouldThrow("new MediaStreamEvent('eventType', { stream: NaN }).stream");
 // Note that valueOf() is not called, when the left hand side is evaluated.
-shouldBeFalse("new MediaStreamEvent('eventType', { stream: {valueOf: function () { return mediaStream; } } }).stream == mediaStream");
-shouldBe("new MediaStreamEvent('eventType', { get stream() { return 123; } }).stream", "null");
+shouldThrow("new MediaStreamEvent('eventType', { stream: {valueOf: function () { return mediaStream; } } }).stream == mediaStream");
+shouldBe("new MediaStreamEvent('eventType', { get stream() { return mediaStream; } }).stream", "mediaStream");
+shouldThrow("new MediaStreamEvent('eventType', { get stream() { return 123; } }).stream");
 shouldThrow("new MediaStreamEvent('eventType', { get stream() { throw 'MediaStreamEvent Error'; } })");
 
 // All initializers are passed.