Purge a number of Mozilla-specific WebIDL

Did a bunch of grepping for `moz*` and searched for "moz" in rustdoc,
deleting anything that looked mozilla-specific. Now there's nothing left
with the "moz" prefix in rustdoc!

crates/web-sys/webidls/enabled/HTMLCanvasElement.webidl

@@ -40,16 +40,4 @@ partial interface HTMLCanvasElement {
   OffscreenCanvas transferControlToOffscreen();
 };
 
-[ChromeOnly]
-interface MozCanvasPrintState
-{
-  // A canvas rendering context.
-  readonly attribute nsISupports context;
-
-  // To be called when rendering to the context is done.
-  void done();
-};
-
-callback PrintCallback = void(MozCanvasPrintState ctx);
-
 callback BlobCallback = void(Blob? blob);