fix corner cases with export (#4699)

fixes #4698
fixes #4700
fixes #4701
fixes #4702

test/compress/exports.js

@@ -70,6 +70,27 @@ defaults_parentheses_4: {
     expect_exact: "export default(function f(){});"
 }
 
+defaults_parentheses_5: {
+    input: {
+        export default (function(a) {
+            console.log(a[0]);
+        }`PASS`);
+    }
+    expect_exact: "export default(function(a){console.log(a[0])})`PASS`;"
+}
+
+defaults_parentheses_6: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        export default !function() {
+            while (!console);
+        }() ? "PASS" : "FAIL";
+    }
+    expect_exact: 'export default(function(){while(!console);})()?"FAIL":"PASS";'
+}
+
 foreign: {
     input: {
         export * from "foo";

test/sandbox.js

@@ -53,7 +53,7 @@ exports.strip_exports = function(code) {
     var count = 0;
     return code.replace(/\bexport(?:\s*\{[^}]*};|\s+default\b(?:\s*(\(|\{|class\s*\{|class\s+(?=extends\b)|(?:async\s+)?function\s*(?:\*\s*)?\())?|\b)/g, function(match, header) {
         if (!header) return "";
-        if (header.length == 1) return "~" + header;
+        if (header.length == 1) return "!!" + header;
         return header.slice(0, -1) + " _" + ++count + header.slice(-1);
     });
 };