enhance if_return (#5330)

lib/compress.js

@@ -3294,7 +3294,8 @@ Compressor.prototype.compress = function(node) {
         function handle_if_return(statements, compressor) {
             var changed = false;
             var parent = compressor.parent();
-            var in_iife = in_lambda && parent && parent.TYPE == "Call";
+            var self = compressor.self();
+            var in_iife = in_lambda && parent && parent.TYPE == "Call" && parent.expression === self;
             var chain_if_returns = in_lambda && compressor.option("conditionals") && compressor.option("sequences");
             var multiple_if_returns = has_multiple_if_returns(statements);
             for (var i = statements.length; --i >= 0;) {
@@ -3371,15 +3372,11 @@ Compressor.prototype.compress = function(node) {
 
                     if (compressor.option("typeofs")) {
                         if (ab && !alt) {
-                            var stats = make_node(AST_BlockStatement, compressor.self(), {
+                            var stats = make_node(AST_BlockStatement, self, { body: statements.slice(i + 1) });
-                                body: statements.slice(i + 1),
-                            });
                             mark_locally_defined(stat.condition, null, stats);
                         }
                         if (!ab && alt) {
-                            var stats = make_node(AST_BlockStatement, compressor.self(), {
+                            var stats = make_node(AST_BlockStatement, self, { body: statements.slice(i + 1) });
-                                body: statements.slice(i + 1),
-                            });
                             mark_locally_defined(stat.condition, stats);
                         }
                     }

test/compress/if_return.js

@@ -395,7 +395,31 @@ if_var_return_2: {
     }
 }
 
-if_var_return_3: {
+if_var_retrn_3: {
+    options = {
+        conditionals: true,
+        if_return: true,
+        sequences: true,
+    }
+    input: {
+        f(function() {
+            var a = w();
+            if (x())
+                return y(a);
+            z();
+        });
+    }
+    expect: {
+        f(function() {
+            var a = w();
+            if (x())
+                return y(a);
+            z();
+        });
+    }
+}
+
+if_var_return_4: {
     options = {
         conditionals: true,
         if_return: true,