Add an option to wrap IIFEs in parenthesis

For #1307.

bin/uglifyjs

@@ -76,6 +76,7 @@ You need to pass an argument to this option to specify the name that your module
     .describe("name-cache", "File to hold mangled names mappings")
     .describe("pure-funcs", "List of functions that can be safely removed if their return value is not used")
     .describe("dump-spidermonkey-ast", "Dump SpiderMonkey AST to stdout.")
+    .describe("wrap-iife", "Wrap IIFEs in parenthesis. Note: this disables the negate_iife compression option")
 
     .alias("p", "prefix")
     .alias("o", "output")
@@ -130,6 +131,7 @@ You need to pass an argument to this option to specify the name that your module
     .boolean("bare-returns")
     .boolean("keep-fnames")
     .boolean("reserve-domprops")
+    .boolean("wrap-iife")
 
     .wrap(80)
 
@@ -247,6 +249,11 @@ if (ARGS.keep_fnames) {
     if (MANGLE) MANGLE.keep_fnames = true;
 }
 
+if (ARGS.wrap_iife) {
+    if (COMPRESS) COMPRESS.negate_iife = false;
+    OUTPUT_OPTIONS.wrap_iife = true;
+}
+
 if (BEAUTIFY)
     UglifyJS.merge(OUTPUT_OPTIONS, BEAUTIFY);
 

lib/output.js

@@ -67,7 +67,8 @@ function OutputStream(options) {
         screw_ie8        : true,
         preamble         : null,
         quote_style      : 0,
-        keep_quoted_props: false
+        keep_quoted_props: false,
+        wrap_iife        : false,
     }, true);
 
     // Convert comment option to RegExp if neccessary and set up comments filter
@@ -552,7 +553,17 @@ function OutputStream(options) {
     // a function expression needs parens around it when it's provably
     // the first token to appear in a statement.
     PARENS(AST_Function, function(output){
-        return first_in_statement(output);
+        if (first_in_statement(output)) {
+            return true;
+        }
+
+        if (output.option('wrap_iife')) {
+            var p = output.parent();
+            console.log()
+            return p instanceof AST_Call && p.expression === this;
+        }
+
+        return false;
     });
 
     // same goes for an object literal, because otherwise it would be

test/compress/wrap_iife.js

@@ -0,0 +1,33 @@
+wrap_iife: {
+    options = {
+        negate_iife: false,
+    }
+    beautify = {
+        wrap_iife: true,
+    }
+    input: {
+        (function() {
+            return function() {
+                console.log('test')
+            };
+        })()();
+    }
+    expect_exact: '(function(){return function(){console.log("test")}})()();'
+}
+
+wrap_iife_in_return_call: {
+    options = {
+        negate_iife: false,
+    }
+    beautify = {
+        wrap_iife: true,
+    }
+    input: {
+        (function() {
+            return (function() {
+                console.log('test')
+            })();
+        })()();
+    }
+    expect_exact: '(function(){return(function(){console.log("test")})()})()();'
+}