fail installation when puppeteer errors downloading chromium (puppete…

…er#654)

This patch starts failing npm installation when puppeteer errors downloading chromium.

install.js

@@ -36,11 +36,8 @@ Downloader.downloadRevision(platform, revision, onProgress)
     .catch(onError);
 
 function onError(error) {
-  console.error(`ERROR: Failed to download chromium r${revision}!
-- Download chromium manually:
-    ${revisionInfo.url}
-- Extract chromium into ${revisionInfo.folderPath}
-  * Chromium executable should be at ${revisionInfo.executablePath}`);
+  console.error(`ERROR: Failed to download Chromium r${revision}! Set "PUPPETEER_SKIP_CHROMIUM_DOWNLOAD" env variable to skip download.`);
+  process.exit(1);
 }
 
 let progressBar = null;