fix corner cases in rename & varify (#4955)

fixes #4954

test/compress/const.js

@@ -1535,3 +1535,56 @@ issue_4848: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4954_1: {
+    rename = true
+    input: {
+        (function() {
+            {
+                const a = "foo";
+                console.log(a);
+            }
+            {
+                const a = "bar";
+                console.log(a);
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            {
+                const a = "foo";
+                console.log(a);
+            }
+            {
+                const a = "bar";
+                console.log(a);
+            }
+        })();
+    }
+    expect_stdout: true
+}
+
+issue_4954_2: {
+    mangle = {}
+    input: {
+        "use strict";
+        const a = null;
+        (function(b) {
+            for (const a in null);
+            for (const a in b)
+                console.log("PASS");
+        })([ null ]);
+    }
+    expect: {
+        "use strict";
+        const a = null;
+        (function(o) {
+            for (const n in null);
+            for (const n in o)
+                console.log("PASS");
+        })([ null ]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/drop-unused.js

@@ -3080,11 +3080,9 @@ issue_4235: {
         })();
     }
     expect: {
-        (function() {
-            f = console.log(f),
-            void 0;
-            var f;
-        })();
+        void function() {
+            var f = console.log(f);
+        }();
     }
     expect_stdout: "undefined"
 }

test/compress/varify.js

@@ -575,3 +575,41 @@ issue_4933_2: {
     }
     expect_stdout: "undefined"
 }
+
+issue_4954: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+        varify: true,
+    }
+    input: {
+        "use strict";
+        (function() {
+            {
+                let a = console;
+                console.log(typeof a);
+            }
+            {
+                let a = function() {};
+                a && console.log(typeof a);
+            }
+        })();
+    }
+    expect: {
+        "use strict";
+        (function() {
+            var a = console;
+            console.log(typeof a);
+            {
+                let a = function() {};
+                a && console.log(typeof a);
+            }
+        })();
+    }
+    expect_stdout: [
+        "object",
+        "function",
+    ]
+    node_version: ">=4"
+}