use codicon for notebook find widget

src/vs/workbench/contrib/codeEditor/browser/find/simpleFindReplaceWidget.css

@@ -114,33 +114,6 @@
 	cursor: pointer;
 }
 
-.monaco-workbench .simple-fr-find-part .button.previous {
-	background-image: url('images/chevron-previous-light.svg');
-}
-
-.monaco-workbench .simple-fr-find-part .button.next {
-	background-image: url('images/chevron-next-light.svg');
-}
-
-.monaco-workbench .simple-fr-find-part .button.close-fw {
-	background-image: url('images/close-light.svg');
-}
-
-.hc-black .monaco-workbench .simple-fr-find-part .button.previous,
-.vs-dark .monaco-workbench .simple-fr-find-part .button.previous {
-	background-image: url('images/chevron-previous-dark.svg');
-}
-
-.hc-black .monaco-workbench .simple-fr-find-part .button.next,
-.vs-dark .monaco-workbench .simple-fr-find-part .button.next {
-	background-image: url('images/chevron-next-dark.svg');
-}
-
-.hc-black .monaco-workbench .simple-fr-find-part .button.close-fw,
-.vs-dark .monaco-workbench .simple-fr-find-part .button.close-fw {
-	background-image: url('images/close-dark.svg');
-}
-
 .monaco-workbench .simple-fr-find-part .button.disabled {
 	opacity: 0.3;
 	cursor: default;

src/vs/workbench/contrib/codeEditor/browser/find/simpleFindReplaceWidget.ts

@@ -147,7 +147,7 @@ export abstract class SimpleFindReplaceWidget extends Widget {
 
 		this.prevBtn = this._register(new SimpleButton({
 			label: NLS_PREVIOUS_MATCH_BTN_LABEL,
-			className: 'previous',
+			className: 'codicon codicon-arrow-up',
 			onTrigger: () => {
 				this.find(true);
 			}
@@ -155,7 +155,7 @@ export abstract class SimpleFindReplaceWidget extends Widget {
 
 		this.nextBtn = this._register(new SimpleButton({
 			label: NLS_NEXT_MATCH_BTN_LABEL,
-			className: 'next',
+			className: 'codicon codicon-arrow-down',
 			onTrigger: () => {
 				this.find(false);
 			}
@@ -163,7 +163,7 @@ export abstract class SimpleFindReplaceWidget extends Widget {
 
 		const closeBtn = this._register(new SimpleButton({
 			label: NLS_CLOSE_BTN_LABEL,
-			className: 'close-fw',
+			className: 'codicon codicon-close',
 			onTrigger: () => {
 				this.hide();
 			}