customElement.define's 2nd param is construct sig (#815)

Previously it was a call signature, but this is not correct.

Author: sandersn

baselines/dom.generated.d.ts

@@ -19255,7 +19255,7 @@ interface BlobCallback {
 }
 
 interface CustomElementConstructor {
-    (): HTMLElement;
+    new (): HTMLElement;
 }
 
 interface DecodeErrorCallback {

inputfiles/overridingTypes.json

@@ -311,6 +311,11 @@
                 "override-signatures": [
                     "(chunk: I, controller: TransformStreamDefaultController<O>): void | PromiseLike<void>"
                 ]
+            },
+            "CustomElementConstructor": {
+                "override-signatures": [
+                    "new (): HTMLElement"
+                ]
             }
         }
     },