Improve handling of dictionary conversions.

LayoutTests/fast/events/constructors/keyboard-event-constructor-expected.txt

Index: LayoutTests/fast/events/constructors/keyboard-event-constructor-expected.txt
diff --git a/LayoutTests/fast/events/constructors/keyboard-event-constructor-expected.txt b/LayoutTests/fast/events/constructors/keyboard-event-constructor-expected.txt
index 28135c5c780e5a96cb49bc357f1bb092b7e7fa5a..68a4ed4d2f41d21e3487e906c2bc3031b96730a9 100644
--- a/LayoutTests/fast/events/constructors/keyboard-event-constructor-expected.txt
+++ b/LayoutTests/fast/events/constructors/keyboard-event-constructor-expected.txt
@@ -21,19 +21,20 @@ PASS new KeyboardEvent('eventType', { cancelable: false }).cancelable is false
 PASS new KeyboardEvent('eventType', { cancelable: true }).cancelable is true
 PASS new KeyboardEvent('eventType', { view: window }).view is window
 PASS new KeyboardEvent('eventType', { view: this }).view is this
-PASS new KeyboardEvent('eventType', { view: testObject }).view is null
-PASS new KeyboardEvent('eventType', { view: document }).view is null
+PASS new KeyboardEvent('eventType', { view: testObject }).view threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { view: document }).view threw exception TypeError: The 'view' property does not have a Window type..
 PASS new KeyboardEvent('eventType', { view: undefined }).view is null
 PASS new KeyboardEvent('eventType', { view: null }).view is null
-PASS new KeyboardEvent('eventType', { view: false }).view is null
-PASS new KeyboardEvent('eventType', { view: true }).view is null
-PASS new KeyboardEvent('eventType', { view: '' }).view is null
-PASS new KeyboardEvent('eventType', { view: 'chocolate' }).view is null
-PASS new KeyboardEvent('eventType', { view: 12345 }).view is null
-PASS new KeyboardEvent('eventType', { view: 18446744073709551615 }).view is null
-PASS new KeyboardEvent('eventType', { view: NaN }).view is null
-PASS new KeyboardEvent('eventType', { view: {valueOf: function () { return window; } } }).view == window is false
-PASS new KeyboardEvent('eventType', { get view() { return 123; } }).view is null
+PASS new KeyboardEvent('eventType', { view: false }).view threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { view: true }).view threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { view: '' }).view threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { view: 'chocolate' }).view threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { view: 12345 }).view threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { view: 18446744073709551615 }).view threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { view: NaN }).view threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { view: {valueOf: function () { return window; } } }).view == window threw exception TypeError: The 'view' property does not have a Window type..
+PASS new KeyboardEvent('eventType', { get view() { return window; } }).view is window
+PASS new KeyboardEvent('eventType', { get view() { return 123; } }).view threw exception TypeError: The 'view' property does not have a Window type..
 PASS new KeyboardEvent('eventType', { get view() { throw 'KeyboardEvent Error'; } }) threw exception KeyboardEvent Error.
 PASS new KeyboardEvent('eventType', { keyIdentifier: 'koakuma' }).keyIdentifier is "koakuma"
 PASS new KeyboardEvent('eventType', { keyIdentifier: '' }).keyIdentifier is ""