improve --reduce-test (#5763)

Author: alexlamsl

test/input/reduce/unsafe_math.reduced.js

@@ -1,16 +1,10 @@
 // (beautified)
-var b = 0;
-
 var expr2 = (0 - 1 - .1 - .1).toString();
 
-for (var key2 in expr2) {
-    --b;
-}
-
-console.log(b);
-// output: -19
+console.log(expr2);
+// output: -1.2000000000000002
 // 
-// minify: -4
+// minify: -1.2
 // 
 // options: {
 //   "compress": {

test/mocha/reduce.js

@@ -236,9 +236,9 @@ describe("test/reduce.js", function() {
     });
     it("Should report trailing whitespace difference in stringified format", function() {
         var code = [
-            "for (var a in (1 - .8).toString()) {",
+            "[].forEach.call((1 - .8).toString(), function() {",
             "    console.log();",
-            "}",
+            "});",
         ].join("\n");
         var result = reduce_test(code, {
             compress: {

test/reduce.js

@@ -193,7 +193,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
         }
         else if (node instanceof U.AST_BlockStatement) {
             if (in_list && node.body.filter(function(node) {
-                return node instanceof U.AST_Const;
+                return node instanceof U.AST_Const || node instanceof U.AST_Let;
             }).length == 0) {
                 node.start._permute++;
                 CHANGED = true;
@@ -335,19 +335,21 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
         }
         else if (node instanceof U.AST_ForEnumeration) {
             var expr;
-            switch ((node.start._permute * steps | 0) % 3) {
+            switch ((node.start._permute * steps | 0) % 4) {
               case 0:
-                if (node.init instanceof U.AST_Definitions) {
-                    if (node.init instanceof U.AST_Const) break;
-                    if (node.init.definitions[0].name instanceof U.AST_Destructured) break;
-                }
-                expr = node.init;
+                expr = node.object;
                 break;
               case 1:
-                expr = node.object;
+                expr = wrap_with_console_log(node.object);
                 break;
               case 2:
-                if (!has_loopcontrol(node.body, node, parent)) expr = node.body;
+                if (has_loopcontrol(node.body, node, parent)) break;
+                expr = node.body;
+                break;
+              case 3:
+                if (!(node.init instanceof U.AST_Var)) break;
+                if (node.init.definitions[0].name instanceof U.AST_Destructured) break;
+                expr = node.init;
                 break;
             }
             node.start._permute += step;