Make DataTransferItemList.add(data, type) arguments mandatory

LayoutTests/fast/events/drag-dataTransferItemList-expected.txt

Index: LayoutTests/fast/events/drag-dataTransferItemList-expected.txt
diff --git a/LayoutTests/fast/events/drag-dataTransferItemList-expected.txt b/LayoutTests/fast/events/drag-dataTransferItemList-expected.txt
index 76f2752e646efa0d6eddde361e2bc4128ba58015..59e68a84e84b5a1c9a7e971d9f9f5971c63d3ded 100644
--- a/LayoutTests/fast/events/drag-dataTransferItemList-expected.txt
+++ b/LayoutTests/fast/events/drag-dataTransferItemList-expected.txt
@@ -4,30 +4,50 @@ Drag Me
 Drop Here
 Drag handler: 
 Drop handler: 
+Tests drag'n drop and well as DataTransferItemList
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
 Running test with Legacy drag handler and Legacy drop handler
-PASS: 4 === 4
-PASS: sample === sample
-PASS: http://www.google.com/ === http://www.google.com/
-PASS: <em>Markup</em> === <em>Markup</em>
-PASS: hello world === hello world
+PASS testDataTransfer.types.length is 4
+PASS testDataTransfer.types.indexOf("text/plain") >= 0 is true
+PASS testDataTransfer.types.indexOf("text/uri-list") >= 0 is true
+PASS testDataTransfer.types.indexOf("text/html") >= 0 is true
+PASS testDataTransfer.types.indexOf("custom-data") >= 0 is true
+PASS testDataTransfer.getData("text") is "sample"
+PASS testDataTransfer.getData("url") is "http://www.google.com/"
+PASS testDataTransfer.getData("text/html") is "<em>Markup</em>"
+PASS testDataTransfer.getData("custom-data") is "hello world"
 Running test with Legacy drag handler and DataTransferItemList drop handler
-PASS: 4 === 4
-PASS: [{"kind":"string","type":"custom-data"},{"kind":"string","type":"text/html"},{"kind":"string","type":"text/plain"},{"kind":"string","type":"text/uri-list"}] === [{"kind":"string","type":"custom-data"},{"kind":"string","type":"text/html"},{"kind":"string","type":"text/plain"},{"kind":"string","type":"text/uri-list"}]
-PASS: hello world === hello world
-PASS: <em>Markup</em> === <em>Markup</em>
-PASS: sample === sample
-PASS: http://www.google.com/ === http://www.google.com/
+PASS testDataTransfer.items.length is 4
+PASS JSON.stringify(expectedTypes) is JSON.stringify(types)
+PASS testData is expectedTestData
+PASS testData is expectedTestData
+PASS testData is expectedTestData
+PASS testData is expectedTestData
 Running test with DataTransferItemList drag handler and Legacy drop handler
-PASS: 4 === 4
-PASS: sample === sample
-PASS: http://www.google.com/ === http://www.google.com/
-PASS: <em>Markup</em> === <em>Markup</em>
-PASS: hello world === hello world
+PASS testDataTransfer.items.add() threw exception TypeError: Not enough arguments.
+PASS testDataTransfer.items.add("sample") threw exception TypeError: Type error.
+PASS testDataTransfer.types.length is 4
+PASS testDataTransfer.types.indexOf("text/plain") >= 0 is true
+PASS testDataTransfer.types.indexOf("text/uri-list") >= 0 is true
+PASS testDataTransfer.types.indexOf("text/html") >= 0 is true
+PASS testDataTransfer.types.indexOf("custom-data") >= 0 is true
+PASS testDataTransfer.getData("text") is "sample"
+PASS testDataTransfer.getData("url") is "http://www.google.com/"
+PASS testDataTransfer.getData("text/html") is "<em>Markup</em>"
+PASS testDataTransfer.getData("custom-data") is "hello world"
 Running test with DataTransferItemList drag handler and DataTransferItemList drop handler
-PASS: 4 === 4
-PASS: [{"kind":"string","type":"custom-data"},{"kind":"string","type":"text/html"},{"kind":"string","type":"text/plain"},{"kind":"string","type":"text/uri-list"}] === [{"kind":"string","type":"custom-data"},{"kind":"string","type":"text/html"},{"kind":"string","type":"text/plain"},{"kind":"string","type":"text/uri-list"}]
-PASS: hello world === hello world
-PASS: <em>Markup</em> === <em>Markup</em>
-PASS: sample === sample
-PASS: http://www.google.com/ === http://www.google.com/
+PASS testDataTransfer.items.add() threw exception TypeError: Not enough arguments.
+PASS testDataTransfer.items.add("sample") threw exception TypeError: Type error.
+PASS testDataTransfer.items.length is 4
+PASS JSON.stringify(expectedTypes) is JSON.stringify(types)
+PASS testData is expectedTestData
+PASS testData is expectedTestData
+PASS testData is expectedTestData
+PASS testData is expectedTestData
+PASS successfullyParsed is true
+
+TEST COMPLETE