Fixes monaco diff editor color var issues (microsoft#188513)

Author: hediet

src/vs/editor/browser/widget/diffEditorWidget2/diffEditorWidget2.contribution.ts

@@ -14,7 +14,6 @@ import { ILocalizedString } from 'vs/platform/action/common/action';
 import { Action2, MenuId, MenuRegistry, registerAction2 } from 'vs/platform/actions/common/actions';
 import { IConfigurationService } from 'vs/platform/configuration/common/configuration';
 import { ContextKeyEqualsExpr, ContextKeyExpr } from 'vs/platform/contextkey/common/contextkey';
-import './colors';
 
 export class ToggleCollapseUnchangedRegions extends Action2 {
 	constructor() {

src/vs/editor/browser/widget/diffEditorWidget2/diffEditorWidget2.ts

@@ -46,6 +46,7 @@ import { CursorChangeReason } from 'vs/editor/common/cursorEvents';
 import { AudioCue, IAudioCueService } from 'vs/platform/audioCues/browser/audioCueService';
 import { LengthObj } from 'vs/editor/common/model/bracketPairsTextModelPart/bracketPairsTree/length';
 import { Range } from 'vs/editor/common/core/range';
+import './colors';
 
 export class DiffEditorWidget2 extends DelegatingEditor implements IDiffEditor {
 	private readonly elements = h('div.monaco-diff-editor.side-by-side', { style: { position: 'relative', height: '100%' } }, [

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

@@ -392,7 +392,7 @@ export class StandaloneThemeService extends Disposable implements IStandaloneThe
 				colorVariables.push(`${asCssVariableName(item.id)}: ${color.toString()};`);
 			}
 		}
-		ruleCollector.addRule(`.monaco-editor { ${colorVariables.join('\n')} }`);
+		ruleCollector.addRule(`.monaco-editor, .monaco-diff-editor { ${colorVariables.join('\n')} }`);
 
 		const colorMap = this._colorMapOverride || this._theme.tokenTheme.getColorMap();
 		ruleCollector.addRule(generateTokensCSSForColorMap(colorMap));