packages/okam-build/lib/polyfill/prepare.js
function preparePolyfillSupport(polyfill, rootDir, logger) {
    if (!polyfill) {
        return;
    }

    if (!Array.isArray(polyfill)) {
        polyfill = [polyfill];
    }

    polyfill.forEach(info => {
        try {
            ensure(info.desc, info.deps, rootDir);
        }
        catch (ex) {
            logger.warn(ex.toString());
        }
    });
}
function preparePolyfillSupport(polyfill, rootDir, logger) {
    if (!polyfill) {
        return;
    }

    if (!Array.isArray(polyfill)) {
        polyfill = [polyfill];
    }

    polyfill.forEach(info => {
        try {
            ensure(info.desc, info.deps, rootDir);
        }
        catch (ex) {
            logger.warn(ex.toString());
        }
    });
}
Prepare the dependencies of the polyfill to support.

@param {Array.<string>|string} polyfill the polyfill type to support,
`promise` or `async` is currently support type
@param {string} rootDir the project root dir
@param {Object} logger log util