add registerBufferElementProvider (#4402)

src/browser/Types.d.ts

@@ -80,6 +80,7 @@ export interface IPublicTerminal extends IDisposable {
   refresh(start: number, end: number): void;
   clearTextureAtlas(): void;
   reset(): void;
+  registerBufferElementProvider(bufferProvider: IBufferElementProvider): IDisposable;
 }
 
 export type CustomKeyEventHandler = (event: KeyboardEvent) => boolean;
@@ -220,3 +221,7 @@ export interface IRenderDebouncer extends IDisposable {
 export interface IRenderDebouncerWithCallback extends IRenderDebouncer {
   addRefreshCallback(callback: FrameRequestCallback): number;
 }
+
+export interface IBufferElementProvider {
+  provideBufferElements(): DocumentFragment;
+}