fix corner case in `ie8` (#4187)

fixes #4186

2 files changed, 18 insertions, 8 deletions

diff --git a/lib/ast.js b/lib/ast.js
index 08b4b65c..ac779cb9 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -282,9 +282,6 @@ var AST_BlockScope = DEFNODE("BlockScope", "cname enclosed functions make_def pa
 
 var AST_BlockStatement = DEFNODE("BlockStatement", null, {
     $documentation: "A block statement",
-    initialize: function() {
-        this.variables = new Dictionary();
-    },
 }, AST_BlockScope);
 
 var AST_EmptyStatement = DEFNODE("EmptyStatement", null, {
diff --git a/lib/compress.js b/lib/compress.js
index 8c28d450..29cc82a9 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1018,6 +1018,13 @@ merge(Compressor.prototype, {
         return sym instanceof AST_SymbolLambda && def.scope.name === sym;
     });
 
+    function find_scope(compressor) {
+        var level = 0, node;
+        while (node = compressor.parent(level++)) {
+            if (node.variables) return node;
+        }
+    }
+
     function is_lhs_read_only(lhs, compressor) {
         if (lhs instanceof AST_This) return true;
         if (lhs instanceof AST_SymbolRef) {
@@ -6885,7 +6892,7 @@ merge(Compressor.prototype, {
                 && !fn.pinned()
                 && !(fn.name && fn instanceof AST_Function)
                 && (exp === fn || !recursive_ref(compressor, def = exp.definition())
-                    && fn.is_constant_expression(compressor.find_parent(AST_BlockScope)))
+                    && fn.is_constant_expression(find_scope(compressor)))
                 && (value = can_flatten_body(stat))
                 && !fn.contains_this()) {
                 var replacing = exp === fn || compressor.option("unused") && def.references.length - def.replaced == 1;
@@ -8303,9 +8310,16 @@ merge(Compressor.prototype, {
         return lhs instanceof AST_SymbolRef || lhs.TYPE === self.TYPE;
     }
 
+    function find_variable(compressor, name) {
+        var level = 0, node;
+        while (node = compressor.parent(level++)) {
+            if (node.variables) return node.find_variable(name);
+        }
+    }
+
     OPT(AST_Undefined, function(self, compressor) {
         if (compressor.option("unsafe_undefined")) {
-            var undef = compressor.find_parent(AST_BlockScope).find_variable("undefined");
+            var undef = find_scope(compressor).find_variable("undefined");
             if (undef) {
                 var ref = make_node(AST_SymbolRef, self, {
                     name   : "undefined",
@@ -8331,7 +8345,7 @@ merge(Compressor.prototype, {
         if (lhs && is_atomic(lhs, self)) return self;
         if (compressor.option("keep_infinity")
             && !(lhs && !is_atomic(lhs, self))
-            && !compressor.find_parent(AST_BlockScope).find_variable("Infinity"))
+            && !find_scope(compressor).find_variable("Infinity"))
             return self;
         return make_node(AST_Binary, self, {
             operator: "/",
@@ -8346,8 +8360,7 @@ merge(Compressor.prototype, {
 
     OPT(AST_NaN, function(self, compressor) {
         var lhs = is_lhs(compressor.self(), compressor.parent());
-        if (lhs && !is_atomic(lhs, self)
-            || compressor.find_parent(AST_BlockScope).find_variable("NaN")) {
+        if (lhs && !is_atomic(lhs, self) || find_scope(compressor).find_variable("NaN")) {
             return make_node(AST_Binary, self, {
                 operator: "/",
                 left: make_node(AST_Number, self, {