Add missing optional constructor param for Text

Author: alexeagle

baselines/dom.generated.d.ts

@@ -11587,7 +11587,7 @@ interface Text extends CharacterData {
 
 declare var Text: {
     prototype: Text;
-    new(): Text;
+    new(data?: string): Text;
 }
 
 interface TextEvent extends UIEvent {

inputfiles/overridingTypes.json

@@ -1066,5 +1066,12 @@
         "signatures": [
             "new(type: string, touchEventInit?: TouchEventInit): TouchEvent"
         ]
+    },
+    {
+        "kind": "constructor",
+        "interface": "Text",
+        "signatures": [
+            "new(data?: string): Text"
+        ]
     }
  ]