[DevTools] Add dialog type and return value to Page.javascriptDialog{Opening,Closed}.

Source/devtools/protocol.json

Index: Source/devtools/protocol.json
diff --git a/Source/devtools/protocol.json b/Source/devtools/protocol.json
index 3d44b22334c5a9d061a60cad1a09cb17793224bd..090678dbf1739e49d87fc4126ed6f37af69bc981 100644
--- a/Source/devtools/protocol.json
+++ b/Source/devtools/protocol.json
@@ -142,6 +142,13 @@
                     { "name": "timestamp", "type": "number", "optional": true, "hidden": true, "description": "Frame swap timestamp." }
                 ],
                 "hidden": true
+            },
+            {
+                "id": "DialogType",
+                "description": "Javascript dialog type",
+                "type": "string",
+                "enum": ["alert", "confirm", "prompt", "beforeunload"],
+                "hidden": true
             }
         ],
         "commands": [
@@ -510,13 +517,17 @@
                 "name": "javascriptDialogOpening",
                 "description": "Fired when a JavaScript initiated dialog (alert, confirm, prompt, or onbeforeunload) is about to open.",
                 "parameters": [
-                    { "name": "message", "type": "string", "description": "Message that will be displayed by the dialog." }
+                    { "name": "message", "type": "string", "description": "Message that will be displayed by the dialog." },
+                    { "name": "type", "$ref": "DialogType", "description": "Dialog type." }
                 ],
                 "hidden": true
             },
             {
                 "name": "javascriptDialogClosed",
                 "description": "Fired when a JavaScript initiated dialog (alert, confirm, prompt, or onbeforeunload) has been closed.",
+                "parameters": [
+                    { "name": "result", "type": "boolean", "description": "Whether dialog was confirmed." }
+                ],
                 "hidden": true
             },
             {