src/vs/platform/userDataSync/common/settingsMerge.ts/updateIgnoredSettings
export function updateIgnoredSettings(targetContent: string, sourceContent: string, ignoredSettings: string[], formattingOptions: FormattingOptions): string {
	if (ignoredSettings.length) {
		const sourceTree = parseSettings(sourceContent);
		const source = parse(sourceContent);
		const target = parse(targetContent);
		const settingsToAdd: INode[] = [];
		for (const key of ignoredSettings) {
			const sourceValue = source[key];
			const targetValue = target[key];

			// Remove in target
			if (sourceValue === undefined) {
				targetContent = contentUtil.edit(targetContent, [key], undefined, formattingOptions);
			}

			// Update in target
			else if (targetValue !== undefined) {
				targetContent = contentUtil.edit(targetContent, [key], sourceValue, formattingOptions);
			}

			else {
				settingsToAdd.push(findSettingNode(key, sourceTree)!);
			}
		}

		settingsToAdd.sort((a, b) => a.startOffset - b.startOffset);
		settingsToAdd.forEach(s => targetContent = addSetting(s.setting!.key, sourceContent, targetContent, formattingOptions));
	}
	return targetContent;
}