fix corner case in objects (#5214)

fixes #5213

test/compress/objects.js

@@ -198,9 +198,9 @@ numeric_literal: {
     expect_exact: [
         'var obj = {',
         '    0: 0,',
-        '    37: 4,',
-        '    42: 3,',
         '    "-0": 1,',
+        '    42: 3,',
+        '    37: 4,',
         '    o: 5,',
         '    1e42: 8,',
         '    b: 7',
@@ -521,3 +521,25 @@ issue_4415: {
     expect_stdout: "PASS"
     node_version: ">=4"
 }
+
+issue_5213: {
+    options = {
+        objects: true,
+    }
+    input: {
+        var a = "FAIL";
+        console.log({
+            p: a = "PASS",
+            0: a,
+            p: null,
+        }[0]);
+    }
+    expect: {
+        var a = "FAIL";
+        console.log({
+            p: (a = "PASS", null),
+            0: a,
+        }[0]);
+    }
+    expect_stdout: "PASS"
+}

test/sandbox.js

@@ -252,7 +252,7 @@ function run_code_vm(code, toplevel, timeout) {
         var ctx = vm.createContext({ console: console });
         // for Node.js v6
         vm.runInContext(setup_code, ctx);
-        vm.runInContext(toplevel ? "(function(){" + code + "})();" : code, ctx, { timeout: timeout });
+        vm.runInContext(toplevel ? "(function(){\n" + code + "\n})();" : code, ctx, { timeout: timeout });
         // for Node.js v4
         return strip_color_codes(stdout.replace(/\b(Array \[|Object {)/g, function(match) {
             return match.slice(-1);
@@ -266,7 +266,7 @@ function run_code_vm(code, toplevel, timeout) {
 
 function run_code_exec(code, toplevel, timeout) {
     if (toplevel) {
-        code = setup_code + "(function(){" + code + "})();";
+        code = setup_code + "(function(){\n" + code + "\n})();";
     } else {
         code = code.replace(/^((["'])[^"']*\2(;|$))?/, function(directive) {
             return directive + setup_code;