Fixes microsoft/monaco-editor#2140: Do not create a global style sheet unless needed

src/vs/base/browser/ui/codicons/codiconStyles.ts

@@ -8,25 +8,17 @@ import 'vs/css!./codicon/codicon-modifications';
 import 'vs/css!./codicon/codicon-animations';
 
 import { Codicon, iconRegistry } from 'vs/base/common/codicons';
-import { createStyleSheet } from 'vs/base/browser/dom';
-import { RunOnceScheduler } from 'vs/base/common/async';
 
-function initialize() {
-	let codiconStyleSheet = createStyleSheet();
-	codiconStyleSheet.id = 'codiconStyles';
-
-	function updateAll() {
+export const CodiconStyles = new class {
+	onDidChange = iconRegistry.onDidRegister;
+	public getCSS(): string {
 		const rules = [];
 		for (let c of iconRegistry.all) {
 			rules.push(formatRule(c));
 		}
-		codiconStyleSheet.textContent = rules.join('\n');
+		return rules.join('\n');
 	}
-
-	const delayer = new RunOnceScheduler(updateAll, 0);
-	iconRegistry.onDidRegister(() => delayer.schedule());
-	delayer.schedule();
-}
+};
 
 export function formatRule(c: Codicon) {
 	let def = c.definition;
@@ -35,5 +27,3 @@ export function formatRule(c: Codicon) {
 	}
 	return `.codicon-${c.id}:before { content: '${def.character}'; }`;
 }
-
-initialize();

src/vs/editor/standalone/browser/standaloneThemeServiceImpl.ts

@@ -16,6 +16,7 @@ import { ColorIdentifier, Extensions, IColorRegistry } from 'vs/platform/theme/c
 import { Extensions as ThemingExtensions, ICssStyleCollector, IFileIconTheme, IThemingRegistry, ITokenStyle } from 'vs/platform/theme/common/themeService';
 import { IDisposable, Disposable } from 'vs/base/common/lifecycle';
 import { ColorScheme } from 'vs/platform/theme/common/theme';
+import { CodiconStyles } from 'vs/base/browser/ui/codicons/codiconStyles';
 
 const VS_THEME_NAME = 'vs';
 const VS_DARK_THEME_NAME = 'vs-dark';
@@ -193,7 +194,9 @@ export class StandaloneThemeServiceImpl extends Disposable implements IStandalon
 
 	private readonly _environment: IEnvironmentService = Object.create(null);
 	private readonly _knownThemes: Map<string, StandaloneTheme>;
-	private _css: string;
+	private _codiconCSS: string;
+	private _themeCSS: string;
+	private _allCSS: string;
 	private _globalStyleElement: HTMLStyleElement | null;
 	private _styleElements: HTMLStyleElement[];
 	private _theme!: IStandaloneTheme;
@@ -205,10 +208,17 @@ export class StandaloneThemeServiceImpl extends Disposable implements IStandalon
 		this._knownThemes.set(VS_THEME_NAME, newBuiltInTheme(VS_THEME_NAME));
 		this._knownThemes.set(VS_DARK_THEME_NAME, newBuiltInTheme(VS_DARK_THEME_NAME));
 		this._knownThemes.set(HC_BLACK_THEME_NAME, newBuiltInTheme(HC_BLACK_THEME_NAME));
-		this._css = '';
+		this._codiconCSS = CodiconStyles.getCSS();
+		this._themeCSS = '';
+		this._allCSS = `${this._codiconCSS}\n${this._themeCSS}`;
 		this._globalStyleElement = null;
 		this._styleElements = [];
 		this.setTheme(VS_THEME_NAME);
+
+		CodiconStyles.onDidChange(() => {
+			this._codiconCSS = CodiconStyles.getCSS();
+			this._updateCSS();
+		});
 	}
 
 	public registerEditorContainer(domNode: HTMLElement): IDisposable {
@@ -222,7 +232,7 @@ export class StandaloneThemeServiceImpl extends Disposable implements IStandalon
 		if (!this._globalStyleElement) {
 			this._globalStyleElement = dom.createStyleSheet();
 			this._globalStyleElement.className = 'monaco-colors';
-			this._globalStyleElement.innerHTML = this._css;
+			this._globalStyleElement.innerHTML = this._allCSS;
 			this._styleElements.push(this._globalStyleElement);
 		}
 		return Disposable.None;
@@ -231,7 +241,7 @@ export class StandaloneThemeServiceImpl extends Disposable implements IStandalon
 	private _registerShadowDomContainer(domNode: HTMLElement): IDisposable {
 		const styleElement = dom.createStyleSheet(domNode);
 		styleElement.className = 'monaco-colors';
-		styleElement.innerHTML = this._css;
+		styleElement.innerHTML = this._allCSS;
 		this._styleElements.push(styleElement);
 		return {
 			dispose: () => {
@@ -300,8 +310,8 @@ export class StandaloneThemeServiceImpl extends Disposable implements IStandalon
 		let colorMap = tokenTheme.getColorMap();
 		ruleCollector.addRule(generateTokensCSSForColorMap(colorMap));
 
-		this._css = cssRules.join('\n');
-		this._styleElements.forEach(styleElement => styleElement.innerHTML = this._css);
+		this._themeCSS = cssRules.join('\n');
+		this._updateCSS();
 
 		TokenizationRegistry.setColorMap(colorMap);
 		this._onColorThemeChange.fire(theme);
@@ -309,6 +319,11 @@ export class StandaloneThemeServiceImpl extends Disposable implements IStandalon
 		return theme.id;
 	}
 
+	private _updateCSS(): void {
+		this._allCSS = `${this._codiconCSS}\n${this._themeCSS}`;
+		this._styleElements.forEach(styleElement => styleElement.innerHTML = this._allCSS);
+	}
+
 	public getFileIconTheme(): IFileIconTheme {
 		return {
 			hasFileIcons: false,

src/vs/workbench/services/themes/browser/workbenchThemeService.ts

@@ -18,7 +18,7 @@ import { Event, Emitter } from 'vs/base/common/event';
 import { registerFileIconThemeSchemas } from 'vs/workbench/services/themes/common/fileIconThemeSchema';
 import { IDisposable, dispose } from 'vs/base/common/lifecycle';
 import { FileIconThemeData } from 'vs/workbench/services/themes/browser/fileIconThemeData';
-import { removeClasses, addClasses } from 'vs/base/browser/dom';
+import { removeClasses, addClasses, createStyleSheet } from 'vs/base/browser/dom';
 import { IWorkbenchEnvironmentService } from 'vs/workbench/services/environment/common/environmentService';
 import { IFileService, FileChangeType } from 'vs/platform/files/common/files';
 import { URI } from 'vs/base/common/uri';
@@ -36,7 +36,8 @@ import { ILogService } from 'vs/platform/log/common/log';
 import { isWeb } from 'vs/base/common/platform';
 import { ColorScheme } from 'vs/platform/theme/common/theme';
 import { IHostColorSchemeService } from 'vs/workbench/services/themes/common/hostColorSchemeService';
-
+import { CodiconStyles } from 'vs/base/browser/ui/codicons/codiconStyles';
+import { RunOnceScheduler } from 'vs/base/common/async';
 
 // implementation
 
@@ -164,6 +165,17 @@ export class WorkbenchThemeService implements IWorkbenchThemeService {
 			this.installPreferredSchemeListener();
 			this.installRegistryListeners();
 		});
+
+		const codiconStyleSheet = createStyleSheet();
+		codiconStyleSheet.id = 'codiconStyles';
+
+		function updateAll() {
+			codiconStyleSheet.textContent = CodiconStyles.getCSS();
+		}
+
+		const delayer = new RunOnceScheduler(updateAll, 0);
+		CodiconStyles.onDidChange(() => delayer.schedule());
+		delayer.schedule();
 	}
 
 	private initialize(): Promise<[IWorkbenchColorTheme | null, IWorkbenchFileIconTheme | null, IWorkbenchProductIconTheme | null]> {