emit height change event when discard/accept edits (microsoft#227079)

fixes microsoft/vscode-copilot#6938

Author: jrieken

src/vs/workbench/contrib/chat/browser/codeBlockPart.ts

@@ -770,15 +770,11 @@ export class CodeCompareBlockPart extends Disposable {
 			});
 
 			dom.reset(this.messageElement, message);
-
 		}
 
 		const diffData = await data.diffData;
-		if (!diffData) {
-			return;
-		}
 
-		if (!isEditApplied) {
+		if (!isEditApplied && diffData) {
 			const viewModel = this.diffEditor.createViewModel({
 				original: diffData.original,
 				modified: diffData.modified
@@ -801,6 +797,7 @@ export class CodeCompareBlockPart extends Disposable {
 		} else {
 			this.diffEditor.setModel(null);
 			this._lastDiffEditorViewModel.value = undefined;
+			this._onDidChangeContentHeight.fire();
 		}
 
 		this.toolbar.context = {