fix reduce_vars on catch variable

Improved catch handling in `figure_out_scope()` means special case treatment of IE8 is no longer valid in `reset_opt_flags()`.

lib/compress.js

@@ -251,7 +251,6 @@ merge(Compressor.prototype, {
     AST_Node.DEFMETHOD("reset_opt_flags", function(compressor, rescan){
         var reduce_vars = rescan && compressor.option("reduce_vars");
         var toplevel = compressor.option("toplevel");
-        var ie8 = !compressor.option("screw_ie8");
         var safe_ids = [];
         push();
         var suppressor = new TreeWalker(function(node) {
@@ -277,7 +276,7 @@ merge(Compressor.prototype, {
                         d.fixed = false;
                     }
                 }
-                if (ie8 && node instanceof AST_SymbolCatch) {
+                if (node instanceof AST_SymbolCatch) {
                     node.definition().fixed = false;
                 }
                 if (node instanceof AST_VarDef) {

test/compress/reduce_vars.js

@@ -1938,3 +1938,28 @@ pure_getters: {
     }
     expect_stdout: "undefined"
 }
+
+catch_var: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        try {
+            throw {};
+        } catch (e) {
+            var e;
+            console.log(!!e);
+        }
+    }
+    expect: {
+        try {
+            throw {};
+        } catch (e) {
+            var e;
+            console.log(!!e);
+        }
+    }
+    expect_stdout: "true"
+}