improve parenthesis emission (#2196)

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

test/compress/new.js

@@ -82,3 +82,19 @@ new_with_unary_prefix: {
     }
     expect_exact: 'var bar=(+new Date).toString(32);';
 }
+
+dot_parenthesis_1: {
+    input: {
+        console.log(new (Math.random().constructor) instanceof Number);
+    }
+    expect_exact: "console.log(new(Math.random().constructor)instanceof Number);"
+    expect_stdout: "true"
+}
+
+dot_parenthesis_2: {
+    input: {
+        console.log(typeof new function(){Math.random()}.constructor);
+    }
+    expect_exact: "console.log(typeof new function(){Math.random()}.constructor);"
+    expect_stdout: "function"
+}