Implement `DataTransfer` and related interfaces (#34205)

* add datatransfer interfaces

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* implement DataTransfer interface

implemented Constructor, setter and getter for drop_effect and effect_allowed, Items and SetDragImage

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* implement DataTransferItem interface

Implemented Kind, Type, GetAsString, GetAsFile.
Marked DataTransfer as weakReferenceable to access its field
inside DataTransferItemList and DataTransferItem.
Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* implement DataTransferItemList interface

implemented Lenght, Getter, Add, Remove, Clear
Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* added DataTransfer's old interface

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* DataTransfer: implemented GetData, SetData, SetData

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* set Weakref to DataTransfer in DataTransferItemList and DataTransferItem

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* DataTransfer: implemented Types and Files

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* cleanup get_data, set_data, clear_data

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* fix clippy warning

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* add drag data store

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* fix DataTransfer's Types() behaviour

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* DataTransferItem: use the underlying drag data store

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* fix DataTransferItemList's getter and remove

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* fix clippy warnings

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

* update test expectations

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

---------

Signed-off-by: Gae24 <96017547+Gae24@users.noreply.github.com>

3 files changed, 54 insertions, 0 deletions

diff --git a/components/script/dom/webidls/DataTransfer.webidl b/components/script/dom/webidls/DataTransfer.webidl
new file mode 100644
index 00000000000..2e546f0c579
--- /dev/null
+++ b/components/script/dom/webidls/DataTransfer.webidl
@@ -0,0 +1,24 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://html.spec.whatwg.org/multipage/#datatransfer
+
+[Exposed=Window]
+interface DataTransfer {
+  constructor();
+
+  attribute DOMString dropEffect;
+  attribute DOMString effectAllowed;
+
+  [SameObject] readonly attribute DataTransferItemList items;
+
+  undefined setDragImage(Element image, long x, long y);
+
+  /* old interface */
+  readonly attribute /* FrozenArray<DOMString> */ any types;
+  DOMString getData(DOMString format);
+  undefined setData(DOMString format, DOMString data);
+  undefined clearData(optional DOMString format);
+  [SameObject] readonly attribute FileList files;
+};
diff --git a/components/script/dom/webidls/DataTransferItem.webidl b/components/script/dom/webidls/DataTransferItem.webidl
new file mode 100644
index 00000000000..56008f13715
--- /dev/null
+++ b/components/script/dom/webidls/DataTransferItem.webidl
@@ -0,0 +1,15 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://html.spec.whatwg.org/multipage/#datatransferitem
+
+[Exposed=Window]
+interface DataTransferItem {
+  readonly attribute DOMString kind;
+  readonly attribute DOMString type;
+  undefined getAsString(FunctionStringCallback? _callback);
+  File? getAsFile();
+};
+
+callback FunctionStringCallback = undefined (DOMString data);
diff --git a/components/script/dom/webidls/DataTransferItemList.webidl b/components/script/dom/webidls/DataTransferItemList.webidl
new file mode 100644
index 00000000000..efdcb72806e
--- /dev/null
+++ b/components/script/dom/webidls/DataTransferItemList.webidl
@@ -0,0 +1,15 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://html.spec.whatwg.org/multipage/#datatransferitemlist
+
+[Exposed=Window]
+interface DataTransferItemList {
+  readonly attribute unsigned long length;
+  getter DataTransferItem (unsigned long index);
+  [Throws] DataTransferItem? add(DOMString data, DOMString type);
+  [Throws] DataTransferItem? add(File data);
+  [Throws] undefined remove(unsigned long index);
+  undefined clear();
+};