IDL dictionary: Throw a TypeError when an interface member conversion fails

LayoutTests/fast/dom/idl-dictionary-unittest-expected.txt

Index: LayoutTests/fast/dom/idl-dictionary-unittest-expected.txt
diff --git a/LayoutTests/fast/dom/idl-dictionary-unittest-expected.txt b/LayoutTests/fast/dom/idl-dictionary-unittest-expected.txt
index e41d978ddcc25a21a305c6d3af23cab3e3bc3d49..08ea4cb7f82b00636ab599e1e448b7cd47ef76f1 100644
--- a/LayoutTests/fast/dom/idl-dictionary-unittest-expected.txt
+++ b/LayoutTests/fast/dom/idl-dictionary-unittest-expected.txt
@@ -93,6 +93,12 @@ Test for setting invalid object value
 PASS dictionaryTest.set({objectMember: 42}) threw exception TypeError: Failed to execute 'set' on 'DictionaryTest': member objectMember is not an object..
 PASS dictionaryTest.set({objectMember: 'invalid'}) threw exception TypeError: Failed to execute 'set' on 'DictionaryTest': member objectMember is not an object..
 
+Test for setting invalid Element value
+PASS dictionaryTest.set({elementMember: 42}) threw exception TypeError: Failed to execute 'set' on 'DictionaryTest': member elementMember is not of type Element..
+PASS dictionaryTest.set({elementMember: testObject1}) threw exception TypeError: Failed to execute 'set' on 'DictionaryTest': member elementMember is not of type Element..
+PASS dictionaryTest.set({elementMember: []}) threw exception TypeError: Failed to execute 'set' on 'DictionaryTest': member elementMember is not of type Element..
+PASS dictionaryTest.set({elementMember: document}) threw exception TypeError: Failed to execute 'set' on 'DictionaryTest': member elementMember is not of type Element..
+
 Test for passing invalid dictionary values
 PASS dictionaryTest.set(42) threw exception TypeError: Failed to execute 'set' on 'DictionaryTest': parameter 1 ('testingDictionary') is not an object..
 PASS dictionaryTest.set('string') threw exception TypeError: Failed to execute 'set' on 'DictionaryTest': parameter 1 ('testingDictionary') is not an object..