improve parenthesis emission (#2196)

- eliminate `throw` usages
- suppress extraneous parenthesis
  - `new function() {foo.bar()}.baz`
  - `for (function() { "foo" in bar; };;);`

test/compress/loops.js

@@ -436,3 +436,17 @@ do_switch: {
         } while (false);
     }
 }
+
+in_parenthesis_1: {
+    input: {
+        for (("foo" in {});0;);
+    }
+    expect_exact: 'for(("foo"in{});0;);'
+}
+
+in_parenthesis_2: {
+    input: {
+        for ((function(){ "foo" in {}; });0;);
+    }
+    expect_exact: 'for(function(){"foo"in{}};0;);'
+}