src/vs/workbench/services/extensionManagement/common/webExtensionManagementService.ts/WebExtensionManagementService/canInstall
class WebExtensionManagementService:	async canInstall(gallery: IGalleryExtension): Promise<boolean> {
		const compatibleExtension = await this.extensionGalleryService.getCompatibleExtension(gallery);
		if (!compatibleExtension) {
			return false;
		}
		const manifest = await this.extensionGalleryService.getManifest(compatibleExtension, CancellationToken.None);
		if (!manifest) {
			return false;
		}
		if (!this.extensionManifestPropertiesService.canExecuteOnWeb(manifest)) {
			return false;
		}
		return this.webExtensionsScannerService.canAddExtension(gallery);
	}