Remove workaround: base64 support in Netlify Functions

As far as I know, Netlify Functions always support base64 encoding. So
we can remove the code for checking if base64 encoding is supported.

Author: FinnWoelm

lib/templates/netlifyFunction.js

@@ -26,13 +26,6 @@ const callbackHandler = (callback) =>
   };
 
 exports.handler = (event, context, callback) => {
-  // Enable support for base64 encoding.
-  // This is used by next-aws-lambda to determine whether to encode the response
-  // body as base64.
-  if (!process.env.hasOwnProperty("BINARY_SUPPORT")) {
-    process.env.BINARY_SUPPORT = "yes";
-  }
-
   // x-forwarded-host is undefined on Netlify for proxied apps that need it
   // fixes https://github.com/netlify/next-on-netlify/issues/46
   if (!event.multiValueHeaders.hasOwnProperty("x-forwarded-host")) {

lib/templates/reqResMapper.js

@@ -7,9 +7,8 @@ const queryString = require("querystring");
 const http = require("http");
 
 const reqResMapper = (event, callback) => {
-  const base64Support = process.env.BINARY_SUPPORT === "yes";
   const response = {
-    isBase64Encoded: base64Support,
+    isBase64Encoded: true,
     multiValueHeaders: {},
   };
   let responsePromise;
@@ -116,9 +115,7 @@ const reqResMapper = (event, callback) => {
     }
 
     if (response.body) {
-      response.body = Buffer.from(response.body).toString(
-        base64Support ? "base64" : undefined
-      );
+      response.body = Buffer.from(response.body).toString("base64");
     }
     response.multiValueHeaders = res.headers;
     res.writeHead(response.statusCode);