Workaround for wasm2js output minification issue with emscripten (#2185)

* Workaround for wasm2js output minification issue with emscripten

When using emscripten with -O2 and --memory-init-file 0, the
JS minification breaks on this function for memory initialization
setup, causing an exception to be thrown during module setup.

Moving from two 'var' declarations for the same variable to one
should avoid hitting this with no change in functionality (the
var gets hoisted anyway).

emscripten-core/emscripten#8886

Author: bvibber

src/wasm2js.h

@@ -2146,12 +2146,13 @@ void Wasm2JSGlue::emitMemory(
     function(mem) {
       var _mem = new Uint8Array(mem);
       return function(offset, s) {
+        var bytes;
         if (typeof Buffer === 'undefined') {
-          var bytes = atob(s);
+          bytes = atob(s);
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes.charCodeAt(i);
         } else {
-          var bytes = Buffer.from(s, 'base64');
+          bytes = Buffer.from(s, 'base64');
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes[i];
         }

test/wasm2js/address.2asm.js

@@ -83,12 +83,13 @@ var assignasmFunc = (
     function(mem) {
       var _mem = new Uint8Array(mem);
       return function(offset, s) {
+        var bytes;
         if (typeof Buffer === 'undefined') {
-          var bytes = atob(s);
+          bytes = atob(s);
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes.charCodeAt(i);
         } else {
-          var bytes = Buffer.from(s, 'base64');
+          bytes = Buffer.from(s, 'base64');
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes[i];
         }

test/wasm2js/dynamicLibrary.2asm.js

@@ -51,12 +51,13 @@ var assignasmFunc = (
     function(mem) {
       var _mem = new Uint8Array(mem);
       return function(offset, s) {
+        var bytes;
         if (typeof Buffer === 'undefined') {
-          var bytes = atob(s);
+          bytes = atob(s);
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes.charCodeAt(i);
         } else {
-          var bytes = Buffer.from(s, 'base64');
+          bytes = Buffer.from(s, 'base64');
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes[i];
         }

test/wasm2js/dynamicLibrary.2asm.js.opt

@@ -43,12 +43,13 @@ var assignasmFunc = (
     function(mem) {
       var _mem = new Uint8Array(mem);
       return function(offset, s) {
+        var bytes;
         if (typeof Buffer === 'undefined') {
-          var bytes = atob(s);
+          bytes = atob(s);
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes.charCodeAt(i);
         } else {
-          var bytes = Buffer.from(s, 'base64');
+          bytes = Buffer.from(s, 'base64');
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes[i];
         }

test/wasm2js/emscripten.2asm.js

@@ -203,12 +203,13 @@ var writeSegment = (
     function(mem) {
       var _mem = new Uint8Array(mem);
       return function(offset, s) {
+        var bytes;
         if (typeof Buffer === 'undefined') {
-          var bytes = atob(s);
+          bytes = atob(s);
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes.charCodeAt(i);
         } else {
-          var bytes = Buffer.from(s, 'base64');
+          bytes = Buffer.from(s, 'base64');
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes[i];
         }

test/wasm2js/emscripten.2asm.js.opt

@@ -184,12 +184,13 @@ var writeSegment = (
     function(mem) {
       var _mem = new Uint8Array(mem);
       return function(offset, s) {
+        var bytes;
         if (typeof Buffer === 'undefined') {
-          var bytes = atob(s);
+          bytes = atob(s);
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes.charCodeAt(i);
         } else {
-          var bytes = Buffer.from(s, 'base64');
+          bytes = Buffer.from(s, 'base64');
           for (var i = 0; i < bytes.length; i++)
             _mem[offset + i] = bytes[i];
         }