debug: polish repl auto scroll

fixes #9886

src/vs/workbench/parts/debug/electron-browser/repl.ts

@@ -19,7 +19,6 @@ import {Model} from 'vs/editor/common/model/model';
 import {CodeEditor} from 'vs/editor/browser/codeEditor';
 import viewer = require('vs/workbench/parts/debug/electron-browser/replViewer');
 import debug = require('vs/workbench/parts/debug/common/debug');
-import {Expression} from 'vs/workbench/parts/debug/common/debugModel';
 import debugactions = require('vs/workbench/parts/debug/browser/debugActions');
 import replhistory = require('vs/workbench/parts/debug/common/replHistory');
 import {Panel} from 'vs/workbench/browser/panel';
@@ -85,7 +84,7 @@ export class Repl extends Panel {
 			if (panel.getId() === debug.REPL_ID) {
 				const elements = this.debugService.getModel().getReplElements();
 				if (elements.length > 0) {
-					return this.reveal(elements[elements.length - 1]);
+					return this.tree.reveal(elements[elements.length - 1]);
 				}
 			}
 		}));
@@ -100,22 +99,7 @@ export class Repl extends Panel {
 
 			this.refreshTimeoutHandle = setTimeout(() => {
 				this.refreshTimeoutHandle = null;
-
-				const scrollPosition = this.tree.getScrollPosition();
-				this.tree.refresh().then(() => {
-					if (scrollPosition === 0 || scrollPosition === 1) {
-						this.tree.setScrollPosition(1); // keep scrolling to the end unless user scrolled up
-					}
-
-					// If the last repl element has children - auto expand it #6019
-					const elements = this.debugService.getModel().getReplElements();
-					const lastElement = elements.length > 0 ? elements[elements.length - 1] : null;
-					if (lastElement instanceof Expression && lastElement.reference > 0) {
-						return this.tree.expand(elements[elements.length - 1]).then(() =>
-							this.tree.reveal(elements[elements.length - 1], 0)
-						);
-					}
-				}, errors.onUnexpectedError);
+				this.tree.refresh().done(() => this.tree.setScrollPosition(1), errors.onUnexpectedError);
 			}, Repl.REFRESH_DELAY);
 		}
 	}
@@ -192,10 +176,6 @@ export class Repl extends Panel {
 		this.replInput.focus();
 	}
 
-	public reveal(element: debug.ITreeElement): TPromise<void> {
-		return this.tree.reveal(element);
-	}
-
 	public getActions(): actions.IAction[] {
 		if (!this.actions) {
 			this.actions = [